Drunken high jinks and missing trousers – ATV life was one long party, says Chris Tarrant

About to go on air to read the news, Chris Tarrant rushed to the dressing room to get ready. He put on a crisply ironed shirt, tie, suit jacket from Harry Fenton. Then he realised something was missing – his trousers.

"I had no time to hunt for the guilty party," says Tarrant. "I was still in my jeans with holes in the knees. I just threw on a jacket, raced to the studio, and mercifully spent the entire half hour looking a jolly smart boy."

But Tarrant, who is celebrating 50 years since making his television debut on the Midland regional news programme ATV Today, got an even bigger surprise when he discovered who had stolen his trousers – his boss.

The previous week, the rookie reporter had received an email from one of his new fans, a woman from Willenhall whose husband had left her.

"All I really want to do in the world is put my head in your trousers," she wrote.

And when Tarrant sheepishly raised the issue of the trouser theft at an editorial meeting – "It's not a big deal, but somebody has nicked my trousers" – his editor, Mike Warman immediately confessed to being the perpetrator. More than that, he had sent them to the viewer in Willenhall, accompanied by a letter which read: "Thank you for your letter addressed to Christopher Tarrant. He is a great addition to our team, and I am delighted that you want to put your head in his trousers. Accordingly I have enclosed a pair of his most recent trousers and feel free to put your head in them at any time you feel the need. I hope this is a help."

Tarrant joined ATV Today – now Central News – on March 15, 1972. His new book, It's Not a Proper Job, paints a picture of endless alcohol-fuelled high jinks during his time at the Birmingham-based news programme, at a time when regional broadcasting was just taking off.

But it was a career which might never have happened because of Tarrant's incredibly laid-back response when he was given the break that changed his life.

Approaching his mid-20s, Tarrant had little idea of where his career was going. After graduating from Birmingham University he briefly worked as a teacher, but found that was not for him. But it was while working at the Royal Showground in Kenilworth in 1971 that the young man got a first glimpse of what he wanted to do.

"I saw some bloke arrive in a very nice sports car," he recalls. "He combed his hair in the mirror, probably blowing himself a kiss as he got out, and started what seemed like a very short, but very pleasant day's work.

"He did a couple of pieces to camera, standing next to a pedigree Hereford bull. He interviewed a couple of farmers, and talked to the crowd, who all seemed to know him and like him and think him a very nice man. He then did what seemed a fairly banal sign-off, and then got back into his sports car and drove off, waving at his admirers as he disappeared out of the showground, leaving his cameraman and sound man to pack up and load their much less impressive vehicles for the drive home. I thought 'that doesn't look like a bad life at all, doesn't look like a proper job'."

Deciding that was the life for him Tarrant borrowed his father's ancient typewriter and wrote a "cringing, bumptious arrogant letter" to every television company in the British Isles. Tarrant says he still grimaces at his words "I am the face of the 1970s, this is your last chance to snap me up."

"I still cringe when I remember that I really did write those words," he says. After a fortnight, the rejections began to pour in, with broadcasters promising to keep his letter "on file".

"What any prospective employee for any company needs to know from the off is that there is no such thing as a file," he says. "The file is the dustbin." But two of the broadcasters – ATV in Birmingham and Yorkshire Television in Leeds – did not put his letters "on file", but invited him to interviews.

"I think mainly to see what sort of lunatic actually wrote this absurd, egotistic, rambling letter," he says. His bold letter had paid off after all.

Both of them offered him work, but Tarrant decided he preferred Birmingham, having spent his time at university there. "It was a lot closer to my mum for my washing," he adds.

He was offered employment on a week-to-week casual basis, and was asked so start as soon as possible. That was in October, 1971, but it was not until the following March that he finally got round to showing up for work.

"I was on the dole, living with my first wife, very happily, in Weymouth," he says.

"I was drinking excellent Dorset beers every night, and fishing every single day. I told executives at ATV I was writing a screenplay, which they seemed to accept. They must have been incredibly naive. When you consider the original offer of the job – an offer of one week's work made in the October of the year before – quite how I managed to hang it out that long is just extraordinary and idiotic."

Tarrant shudders when he looks at how close he came to throwing his entire career away before it had even begun.

"It is a terrible indication of my totally irresponsible attitude to any thoughts for my career," he says. "I seemed to have no thoughts at all about the seriousness of being offered a job that most young guys in the country would have given their right arm for, and what was to become a very lucky, privileged existence for myself and my kids for the next 50 years."

The book, which Tarrant insists is not an autobiography, recalls the TV industry of the early 1970s as a hedonistic place to work. He recalls features editor John Swallow "showing him the ropes" by taking him to The Crown pub in Broad Street, Birmingham, where he "poured pints of beer down my neck". For the next 10 years, the working day would begin with "the livener" followed by a couple more drinks at lunchtime, and more booze in the green room during and after the show.

"There were bars in every TV station in Britain. They've all gone now, along with a lot of the fun. A lot of the very best television ideas were dreamed up in the bars of television studios all over the UK. I think all of mine were."

He describes Swallow – who died in 2008 – as a lifelong friend, and one of the nicest and funniest men he ever met. Mike Warman, his news editor, was outwardly more sensible, but also a real personality, he says.

"Bob was always smart, but Mike was absolutely immaculate," he says. "He looked exactly the same every single day of his life, perfectly combed hair, nice expensive glasses, always freshly washed and ironed shirt and tie, shiny black shoes, and always the pinstripe suit.

"He was obsessed with punctuality. He always walked into the canteen at exactly 8.10 in the morning. He loved his sports cars, and if he was even a minute early, we would actually watch him going around the block again, so that he came in exactly on time."

He recalls a maverick director called Roger Thomas – another lover of fast cars – who one day decided to cut the 90-second closing credits from the bulletin to allow more time for the programme. For this act of insubordination, Thomas was given a written warning that failure to credit "Senior Cameraman AN Other, Sound Man AN Other" and so on would result in immediate dismissal. Thomas responded by running the credits the next day, referring to each member of the team as "AN Other". The management were furious, but couldn't sack him because he had followed their instructions to the letter. It was agreed that from then on, the closing credits would be shorter.

On another occasion, Tarrant says the news team returned from the pub late in the afternoon to find only political editor Reg Harcourt in the newsroom, in the middle of what was clearly a very important conversation with a cabinet minister.

"For no reason that I can even being to think of, we put Reg and his phone upside down in a large plastic dustbin," he says.

"Reg, totally unfazed by our silly schoolboy antics, carried on his conversation with the minister, upside down in the dustbin, for another full five or six minutes.

"And, righting himself, emerged to wild applause from whole office," says Tarrant. "It was all a bit of a lads' culture."

Tarrant admits he wasn't the best hard news reporter, struggling to hide his contempt for the politicians and trade union officials he would usually find himself interviewing, but did manage to carve out a niche specialising in the local eccentrics. Then one week in 1973, ATV's continuity announcer ran a competition for children on Saturday morning, the response to which convinced his bosses that there could be a great untapped market. At that time, weekend children's television consisted of old cowboy films and cartoons, but ATV decided to liven it up by wrapping it all up in a new morning programme called Today Is Saturday: Watch and Smile – or Tiswas for short.

"I remember being thrilled at getting an extra 25 quid a week for three whole hours of live TV," he says. "It was very cheap, but we were very cheerful." Tarrant says the wacky ideas from larger-than-life director Peter Harris led to the ratings going through the roof, and Tiswas gradually went national as the madcap mayhem was taken up by networks around the country.

"By the time Sally James and Lenny Henry joined us we were being nominated for every award, and its success forced the BBC to try to compete with its own rather safe, drab little Saturday morning offering called the Multi-Coloured Swap Shop, hosted by Noel Edmonds with his Division Four footballers' haircut."

But while Tiswas, with its custard pies, dead-fly dances and bucket-of-water song became must-watch television for a generation, his bosses on the news programme were becoming concerned about Tarrant's on-screen double life.

"They started to talk about a 'credibility gap'. I'd be reporting on a bus crash on Friday evening, and then I'd be throwing buckets of water over people on a Saturday morning," he says.

"'You've got to choose,' they said, 'buses or buckets?', certain of course that in the long term I would obviously go for buses. 'Well sorry," I said, to all of their amazement, 'it's got to be buckets'."

*It's Not a Proper Job: Stories from 50 years in TV by Chris Tarrant, published by Great Northern Books, is on sale now priced £17.99.