Veronica Castillo

Joint Head of Production

Ronnie is responsible for all production management aspects of key new projects, particularly those with international production dimensions. She has a wealth of production expertise working as a freelance co-producer and line Producer on a number of high-profile film and TV titles over the past twenty years, including The Mark of Cain, Blind Flight, the multiple BAFTA-winning Sex Traffic, and more recently Strikeback III, Birdsong and Zen.

Prior to embarking on her television career, Ronnie was director of Wallsend Young People’s Theatre, teaching drama to students from schools in the North Tyneside area, mentoring two youth theatres and taking some of their productions to the Edinburgh Fringe Festival.


Billy Cook

Script Editor

Billy has a degree in Creative Writing from Bath Spa University and has been with Mammoth Screen since joining as a runner in October 2012. In his spare time he writes and dreams of things dramatic and ludicrous.


Howard Ella

Joint Head of Production

Howard joins Mammoth Screen having spent the last 15 years Producing and Line Producing dramas such as ‘An Inspector Calls’, ‘Lewis’, ‘Monroe, ‘Mount Pleasant’ and ‘5 Days’.

Howard started in the industry as a runner at Yorkshire Television and has worked in most areas of production.

Outside of Mammoth Howard sits on the board of the Milton Rooms, an arts venue in Malton and writes and directs pantomimes and charity murder mysteries in his native county of Yorkshire.


Charlotte Frings

Production & Office Co-ordinator

Charlotte Frings started her career at the Royal Court Theatre and then became Executive Assistant to the Head of Working Title, where she assisted on productions such as Last of the Blonde Bombshells, Randall and Hopkirk (Deceased) and Ready When You Are Mr McGill.

She then helped start up Big Tree Productions, whose production credits include Diverted, Abroad and cult Australian television series Woodley.

She was the UK Production Coordinator of Falcón, Mammoth Screen’s 2012 production for Sky Atlantic.


James Gandhi

Script Editor

James joined Mammoth in May 2016 after working on the scripted comedy and drama development slates at FremantleMedia. He began his career in front of the camera, before moving to the other side to write for and develop the final two series of CBBC’s ‘Dani’s House’. He has a degree in English from Oxford University.


Chelsea Goslin-Minter

Executive Assistant

Chelsea joined Mammoth as the Office Runner in November 2014, shortly after graduating from Middlesex University with a degree in Theatre Arts. She has since progressed to the Executive Assistant to Damien Timmer, Rebecca Keane and Karen Thrussell. In her spare time, Chelsea loves to read, take photos and also writes her own blog.


Mark Hammond

Financial Controller

Mark joined the Mammoth Screen finance team in September 2015 as Financial Controller, adding an extra layer of support in the central finance team. Mark joins having spent the last 4 years working at ITV within the PLC finance team and more recently as financial support for the overseas production offices.



Felicity Harrison

Finance Assistant

Felicity graduated in 2015 with a degree in Classics from The University of Kent, including a year abroad at The University of California. She joined Mammoth as Finance Assistant in August 2017, having previously worked as an Executive Assistant at a high end men’s fashion magazine.


Laura Johnston

Business Affairs Manager

After studying law at Durham University, Laura was a solicitor at a leading commercial law firm before joining Mammoth in July 2016 as a Business Affairs Manager. Laura is based in the Belfast office.


Rebecca Keane

Creative Director

Rebecca has worked at Mammoth since its launch, overseeing the development slate and executive-producing various shows.

Before joining Mammoth, Rebecca was an executive producer at ITV Productions, working on a wide range of shows including Ballet Shoes, Whatever Love Means, Dracula, The History of Mr Polly, Walk Away and I Stumble, Jericho, Fallen, Daddy’s Girl, and Where the Heart Is.

Rebecca produced Close and True for United Productions and was script executive on In the Name of Love, Touching Evil, and An Unsuitable Job for a Woman. Before this she script-edited Peak Practice for Carlton TV. She studied SPS at the University of Cambridge, ultimately abandoning a PhD to work in TV.


Alexandra Kosevic

Production Executive

Over 20 years experience working in Production across feature films, singles and series television in the UK and abroad. Currently undertaking Ashridge’s inaugural MBA for the Creative Industries.


Preethi Mavahalli

Executive Producer

Preethi joined Mammoth in 2011. During that time, she has Executive Produced Tripped for E4 and NW for BBC2. NW was recently nominated for two 2017 BAFTA British Academy Television Awards in the Leading Actress and Single Drama categories.

Upcoming shows include The City & The City written by Tony Grisoni and directed by Tom Shankland for BBC2 and Next of Kin written by Paul Rutman and Natasha Narayan for ITV.

Also coming soon are adaptations of The War of the Worlds and Noughts & Crosses for BBC One and The Serpent, the true story of Charles Sobhraj and how he was brought to justice by Herman Knippenberg.

Prior to joining Mammoth, Preethi worked in development at Film4, and at Film London on the micro-budget feature film scheme Microwave, where she worked across the slate of films from development through to exhibition – including the BAFTA-nominated Shifty and Ben Drew’s directorial debut Ill Manors.

She also made a number of short films including a Random Act for Channel 4 directed by The Streets’ Mike Skinner. She read History at the University of Oxford.


Alice McArdle

Script Editor

Alice graduated from University of Manchester with a degree in history. She then spent three years in various roles at BBC Drama North, in development and production, before joining Mammoth in 2017, as assistant script editor for Victoria series 2.


Melanie Morris

Head of Business Affairs

Melanie joined Mammoth in January 2012. Previously she worked in private practice, advising a range of UK production companies, and was a production lawyer at Endemol UK and Avalon Television. Prior to this she worked in corporate law.

Before training as a lawyer, Melanie worked in television production and development. She read English at the University of Oxford and has a masters from Trinity College Dublin in Anglo-Irish literature.


James Penny

Commercial Director

James is primarily responsible for all Mammoth’s commercial and business affairs, having joined the company in 2012. From 2006 he was a lawyer in private practice, advising many of the UK’s leading television production companies as well as agents, broadcasters and financiers. He acted for Mammoth throughout this time, and played a leading role in the launch of the company. He is also a board member of Northern Ireland Screen.

Between 2003 and 2006, James worked on dozens of drama, comedy programmes and the occasional feature film at Granada Television, eventually becoming Head of Business Affairs (Drama, Comedy and Film). Projects include THE ROYLE FAMILY, PRIME SUSPECT, CRACKER, HENRY VIII, THE QUEEN, SEX TRAFFIC and HOUSEWIFE 49.

Before joining Granada, James trained and worked in the Media Department of a City law firm for over five years.

He read law at Durham University and has a postgraduate diploma in UK, US and EU copyright from King’s College, London.


Aaron Reeves

Production Assistant

After completing his Masters in Theatre from the University of Chichester Aaron began working as a runner at The Farm Group, he soon became an Edit Assistant but switched to the other side of the camera working as part of the AD team on both Feature films and TV.

Aaron joined Mammoth Screen in February 2017 as a Production Assistant. Alongside this he has become an assistant to Preethi Mavahalli, Helen Ziegler and Tom Mullens.


Emily Russell

Production Executive

Emily started working in commercials before finding her home and love in Drama Production as a PA to the independent producer Paul Knight. This led to working as a Line Producer across a variety of series, serials and one offs for the BBC, ITV and many independents over the past 17 years. She first worked with Mammoth in 2016 on the Bafta nominated drama NW.

Prior to this she completed a Masters in Fine Art at Reading University.


Joe Shrubb

Assistant Production Co-ordinator

Joe began his career in the TV industry at the BBC as a floor runner and then a 3rd Assistant Director. He left the BBC to work on various other projects, joining the crew of Mammoth Screen’s Endeavour for their third series. Joe then moved into Mammoth’s head office as the Production Assistant before progressing to Assistant Production Co-ordinator.



Paul Testar

Script Editor

Paul joined Mammoth in 2014 after graduating from Trinity College Dublin with a degree in English Literature. In his spare time he writes, produces and reviews for the theatre and has worked on several productions at the Edinburgh Fringe.


Karen Thrussell

Executive Producer

Karen joined Mammoth in 2012 after two years as Executive Producer at Chorion, looking after the film, TV and stage exploitation of literary estates for writers including Agatha Christie, Georges Simenon, Enid Blyton and Raymond Chandler. She Executive Produced And Then There Were None, Witness for the Prosecution and Poldark series 1,2 and 3 and is currently working on Ordeal by Innocence and Poldark series 4.

Prior to this Karen produced twenty POIROT and MARPLE films for ITV Studios and the two-part thriller IF I HAD YOU. She was also a script editor on MARPLE, POIROT and NIGHT AND DAY.


Damien Timmer

Managing Director

Damien established Mammoth in 2007. Prior to this he was Head of Drama for ITV Productions for five years, overseeing shows including Housewife 49, Lewis, Marple. Poirot, The History of Mr Polly, Walk Away and I Stumble, Jericho, If I Had You, The Brief, London’s Burning, Me and Mrs Jones and Night and Day for ITV, and Ballet Shoes, Dracula, and Casanova (with Red Productions) for the BBC.

Damien worked at United Productions for three years as an Executive Producer on shows including Hearts and Bones for BBC One and Where the Heart Is and Touching Evil for ITV. Before this Damien worked at Central Films and Carlton for four years, producing Peak Practice, developing projects including Frenchman’s Creek, Heat of the Sun, and The Unkown Soldier and script-editing Cadfael, Kavanagh QC and Inspector Morse. 

Damien read history at Oxford University.


Himesh Velani

Assistant Management Accountant

Himesh joined Mammoth in April 2015 as an Accounts Assistant, following previously working for two years in the film industry, as a billing specialist and credit controller for Twentieth Century Fox. He is training to become a qualified accountant.


Ben Westcombe

Office Runner

Ben joined Mammoth in February 2017 as an Office Runner. He has a degree in photography from Bournemouth University and has been involved in television and drama as an actor from a young age. In his spare time he loves to cook and play football.


Jon Williams

Director of Production & Finance

Jon joined Mammoth Screen in 2007 and oversees all of Mammoth’s production and financial affairs. Prior to this he was Production Executive at ITV Productions, overseeing Agatha Christie’s Marple, William and Mary, The Last Detective, Whatever Love Means, Walk Away and I Stumble, The Brief, Dracula and The History of Mr Polly. 

Before this he was Finance Manager for Granada Media working on Prime Suspect, Sex Traffic, Cold Feet, Life Begins, Agatha Christie’s Poirot, Dr Zhivago, Island at War, Henry VIII and The Forsythe Saga. 

Jon cut his production teeth at United Productions working as management accountant and then production accountant on Hearts and Bones and Where the Heart Is . He is a chartered management accountant by training.