It is gratifying indeed to find Gyles Brandreth describing Elizabeth Sweeting, the one-time administrator of the Oxford Playhouse, as “a difficult old cow”. That was my opinion of her, though – such was the deference shown by most of those obliged to deal with her – it was difficult to find anybody who shared it, or dared to say they did.

Gyles’s judgment was confided to his diary in 1975 and only now emerges with the publication of Something Sensational to Read in the Train (John Murray, £25). Running to more than 700 pages with index, the book contains only a fraction of the written record of his activities which the author has kept throughout his life. He says it would take another 50 volumes to present the diaries in full.

I for one – and possibly the only one to judge from the savage tone of some reviews – would be happy to read them all. Whether the partner of my life would be happy for me to do so, though, is far from certain; she has shown great forbearance on the nights when, seated with her before the fire, I have interrupted her reading of her own book every few minutes to recite some new “good bit”.

Often these have been bad bits, at least for the reputation of the person under discussion. From a man usually regarded as Mr Nice – the woolly jumpers, the appearances on Countdown beaming smile firmly in place, the love of pantomime, of teddy bears, of, it would seem, everything in God’s creation; from such a man, abuse is not expected.

Here is a small selection of his put-downs. Of David Frost we are told that he has “very bad skin”, of Lynn Barber that she is “completely unsexy”, of Robin Day that he is “Mr Toad in a bow tie”, of Andrew Lloyd Webber that “he can barely string a sentence together”, of Lord Bramall that he has “terrible dandruff” (unlike Brandreth’s fellow Tory MP Michael Portillo, whose “hair really is impressive at close quarters, a high sheen and not a touch of dandruff”).

Like it? Here’s more. Rita Tushingham: “the bitch”. “God, Robert Robinson is smug” (everybody knows that, Gyles). Michael Winner: “a monster, an arrogant nobody” (ditto). Derek Nimmo: “lived in a caravan until about ten minutes ago”. Melvyn Bragg: “No one rates his novels.” Spike Milligan: “The man is impossible: self-indulgent and not that funny even at his funniest.”

Ronnie Barker is said to be “excited” by dirty seaside postcards, and Molly Parkin to have “pleasured an entire Welsh rugby team” – this does not surprise me, as one who once sat next to her during a boozy Sunday lunch at the Chelsea Arts Club.

His opinion of the Playhouse’s Miss Sweeting was at least formed on the basis of a significant working relationship, both during his days as a thespian undergraduate at New College and a few years later when he returned to organise (most successfully) Oxford Theatre Festivals in 1974 and 1976.

Oxford looms large in sections of the book, for his student life was an eventful one. It not only included his being president of the Oxford Union, the editor of Isis and a leading light in the Oxford University Dramatic Society, but also becoming a member of Lord Longford’s inquiry into porn.

Courting celebrity in this way – in any way – remained a theme of Brandreth’s life; indeed his career was built on it. One quite sees why the Warden of New College, Sir William Hayter – vetoing Gyles’s plan to film auditions for the OUDS Christmas pantomime Cinderella in the college – complained: “We have had enough of Mr Brandreth’s antics.”

Some seven years later, when by chance I happened to be renting Sir William’s delightful home in Stanton St John, I started to meet Brandreth in the run-up to the theatre festivals. The first featured such memorable plays as William Douglas Home’s The Dame of Sark and a revival of Shaw’s St Joan. That in 1976 produced a big success with Denis Cannan’s Dear Daddy, which went on to become a West End hit and was named play of the year.

The first performance of Dear Daddy saw a ruction in the foyer involving Gyles and boozy actor Noel Davis, a member of the production team: “He made a terrible scene, screaming that he did all the work while I took all the credit.”

There was slight difficulty, too, on the press night at which I was present – and not much enjoying it. Years later, my friend and colleague Jayne Gilman, who had kept a record of the evening, sent me a copy of it.

She wrote: “To begin with Chris Gray was involved, and looking back on it I can’t work out why he was. All I know is that when I turned up at the Playhouse there he was in the foyer, flushed and loud and announcing his intention of helping me interview Gayle Hunnicutt. This had not originally seemed a particularly difficult proposition but as it happened it did get complicated, mostly because of Gyles Brandreth. “The trouble was that the actress was starring in the play which was to follow on from the one being premiered that evening, and hers wasn’t being impresarioed – if there is such a verb – by Mr Brandreth, and instead of chattering about that evening’s play the potential audience was collectively peering out into the pouring rain and saying: ‘Where’s Gayle Hunnicutt?’ and ‘Isn’t she the lovely girl who was in that Henry James serial?’ This was clearly not amusing Mr Brandreth one bit, and having Chris hail him across the foyer like someone hailing a yacht across Poole Harbour with a request for information about Gayle Hunnicutt caused him to narrow his eyes in pure hate. [A passage in which are detailed embarrassing revelations is now deleted.] “At the interval Chris bounced to his feet and headed up the aisle loudly announcing that he’d need a strong drink to get over that experience [as I said, I didn’t like the play], and managed to buttonhole Mr Brandreth to demand safe conduct to where Gayle Hunnicutt was. Mr Brandreth, who clearly wanted to drown both of us in a bucket, directed us to a very bare, cold room where the actress and her agent were shivering on small chairs.

“The interview began promisingly enough. Chris had gone in search of drinks, and the photographer had not yet arrived, so I was able to get some questions in. The actress was beautiful and terrifyingly thin; her wrists were like sticks of celery. She was very nervous, oddly, and seemed pleased to be asked ‘serious’ questions. The photographer arrived and started to pile up chairs and clamber on to a piano to get the shot he wanted, for reasons best known to himself, and Chris reappeared with a tray of drinks, talking loudly. “It was at this point that Gyles Brandreth swept back into the room, waving his hands. “Loves,” he said, “loves. Absolute emergency. Could this poor dear use the phone?” And into the room surged an absolutely enormous woman in a yellow chiffon evening dress like a spare lavatory roll cover, carrying a furled black umbrella. She grabbed the phone, and wept into it. It appeared to be something about a dog. Nothing will ever convince me it was not a piece of wrecking by Mr Brandreth, and very effective it was, I must say.

“Chris and Mr Brandreth were by now doing a sort of Morris dance in the middle of the room with the drinks tray between them, and shouting apparent pleasantries through gritted teeth at each other. The photographer attempted to get on to a rather ornate mantelpiece, and the agent sat on the window sill and bit his nails. Gayle Hunnicutt and I rather gave up trying to compete.”

Fun, eh? I wonder if Gyles’s account of all this is somewhere among his unpublished diaries. If so, I would love to read it.

Final thought: a book of amusing misprints is one of the very few volumes that Gyles seems not to have written. If he ever did, he could include that for Reresby Sitwell in this book: ‘Rearsby Sitwell’. It’s the juxtaposition of the ‘rear’ and the sitting well that does it.