He has been freelancing since January 1974, and his output includes 14 years as a member of the This Is Your Life scriptwriting team, and he has devised several television series including Who's the Greatest? (ITV, 1980s), The Games of 48 and Over the Moon, Brian (with Brian Moore, ITV 1990s), Petrolheads (BBC2 2006); Ricky's Joke Shop (with Ricky Tomlinson, BBC Pilot 2005); he co-produced 63 editions of Stand and Deliver (Sky TV, 1990s), presented by Mike Reid and featuring the likes of Bernard Manning, Cannon & Ball, Ted Rogers, Frank Carson, Stan Boardman, Jim Bowen, Ted Robbins etc. He has collaborated as scriptwriter and co-producer with Top Gear director Brian Klein on more than 50 sports-based videos/DVDs, featuring celebrities such as Gordon Ramsay, Ray Winstone, Alan Hansen, John Motson, Dickie Bird, Frank Bruno, Frankie Dettori, Lawrence Dallaglio, Harry Carpenter, and Jimmy Greaves. He was also scriptwriter for one of the first VHS football videos back in 1981/82, Tottenham: The First 100 Years, presented by Jimmy Greaves. It is now 'an antique' and much sought after by Spurs supporters. Giller recently came out of the closet as a Spurs follower, after many seasons as a press box neutral. He gives all profits from sales of his Tottenham-themed books to the Tottenham Tribute Trust, that helps old players who have hit difficult times.

Giller was a boxing PR for promoters Harry Levene and Mike Barrett, and worked closely with his best pal Terry Lawless in the projection of his star-studded stable of boxers including Frank Bruno, Jim Watt, Maurice Hope, John H. Stracey and Charlie Magri. He also worked as a member of Muhammad Ali's PR team in several of his European fights and counted The Greatest as a good friend. His 99th book focuses on Ali's career.

For several years he collaborated with his old friend Eric Morecambe on a Sportsmile column for the Daily Express and in the Titbits magazine; he also worked on articles with Benny Hill and Tommy Cooper and scripted an adult pantomime for Mike Reid and Barbara Windsor called Pussy In Boots (also featuring Ted Robbins and John Altman). He and Ricky Tomlinson combined with Top Gear director Brian Klein on a BBC comedy pilot called Ricky's Joke Shop., starring Ricky, Jim Bowen and Norman Collier, with a guest appearance by then England goalkeeper David Seaman, who dropped everything he was handed in the shop (well Giller thought it was funny).

His output has also included crosswords and puzzle games with The Times, Daily and Sunday Express, The Sun, Sunday Telegraph and London Evening News. He has compiled the annual Times Sports Jumbo Crossword for 30 consecutive years. Giller was the argument-settling Judge of The Sun for ten years, and he and his sports statistician son Michael set the 2,000 questions for the DVD version of Football Trivial Pursuit. With his then partner Peter Lorenzo and associate Malcolm Rowley, Giller created one of the first major pub quiz competitions in 1974. It was called What's Yours? and had 64 competing pubs in a series sponsored by the Charrington's chain in south-east England. He writes a regular column reflecting on the changing face of newspapers on the Sports Journalists' Association website. His book output includes the following titles