Why did Simon Thurley allow English Heritage, the august body of which he is chief executive, to co-operate with the BBC on a documentary series (Fridays, 9pm)? My guess is that he made the mistake of thinking that he would be in control, and that he and his organisation would emerge with their reputations intact, or even enhanced. But the truth is that you can’t control television – any reality star can tell you this – and, naturally, they do not come out of it at all well.

Patrick Forbes, the series director, is a brilliant satirist with a keen eye for the absurd, and Thurley, with his posh, excitable manner, is the perfect subject – the more platitudes Thurley utters, the more the camera loves him. A lot of people will have seen this (1 May), the second in the four-part series, which was about his exploits at Park Hill in Sheffield, and thought, “What an utter twit.” A few might even have cancelled their annual memberships.

The decision by English Heritage, in 1998, to recommend the listing of Park Hill, a brutalist complex of flats that dates from the 1950s, was among the most controversial it has ever made: many in the city would like it to be pulled down. But I have always been in favour (I was born in Sheffield, and my family still lives there). It’s not only that I am an enthusiast for 20th-century architecture; I also admire the plans for its rehabilitation, which Sheffield Council, the owner of the site, put in the hands of the hip developer Urban Splash. Its architect has taken the restoration of Le Corbusier’s Unité d’Habitation in Marseilles as his model, and his ideas seem to me to be both feasible and thrilling. If English Heritage had not listed Park Hill, this would not have happened. A significant and potentially beautiful building would have been demolished, and a load of banal rabbit hutches thrown up in its place.

But . . . disaster! No sooner had the deal been done than the credit crunch hit. This film began in 2007 as Urban Splash began its work, and it ended in February 2009, by which time the renovation had ground to a halt, thanks to financing problems. Naturally, Forbes emphasised the farcical side of all this, helped by the obligatory soundtrack of sarky glockenspiels. How could he resist? All these middle-class boys getting excited about industrial concrete! Giles Proctor, English Heritage’s supposed concrete expert, wore tweedy stuff and a signet ring the size of the royal seal. Even better, what had at first looked like a brave step by English Heritage now seemed plain foolhardy.

Denuded of its bricks, the building’s concrete frame resembles nothing so much as a multi-storey car park, and is in a more fragile state than ever. As a result, it is still under threat of demolition, listed or not; a bailout by the government to the tune of £39m will see it through in the short term, but not much further.

I think Park Hill is important – part of the story of Britain, and of our architecture – so I still believe the decision to list it was right. Just as we can’t base such judgements on love, or hate, so we cannot base them purely on grounds of financial expediency. But did Thurley articulate this? No, he did not. He just trotted elegantly around, breathlessly pronouncing it as a marvellous piece of “sculpture”. Forbes asked him whether he regretted the listing, and English Heritage’s involvement with the project, given more recent events. This, he argued, was an unfair question. “Not even the Prime Minister knows what is going to happen!” he said. What? This is completely beside the point. If Thurley believed in the decision to list in 2007, then he must believe in it now; it is his duty to explain to sceptical viewers, the majority of whom will have taken one look at Park Hill and hated it, that such a recommendation was based on sound criteria.

Forbes had neatly skewered him, simply by asking a straightforward question, and he was duly revealed, in my eyes, as another blustering self-publicist. Perhaps English Heritage could list his ego next, given that it is now in the business of postwar monoliths.