The best way to appreciate something is to imagine what life would have been like without it.

In the case of Channel 4 that would mean no Shameless, Big Brother, Queer as Folk, Ali G – the list goes on and on. Ever since it started, C4 has been different. My own personal memory of the beginning was watching Brookside, and for the first time seeing a soap that I thought I could relate to. The houses in which it was shot were purpose-built and entirely genuine – therefore, it felt as though their inhabitants were also real.

It’s some achievement for C4: to have originated an industry we can no longer live without

It was groundbreaking advances like this that set C4 apart. Always it has been pushing the boundaries, setting new standards. There’s been a radicalism to its programming that even now, and despite increased competition, it has never lost.

While the on-screen formula is well known and the hits rightly celebrated, what is less obvious is the off-screen structure that has made it possible. Brookside, for instance, was produced by an independent company. As a result, undoubtedly, the sort of script discussions that might stifle creativity in a large corporation simply did not occur – so Brookside decided to show the first pre-watershed lesbian kiss on British TV, for example, and got on with it.

I once helped make a Dispatches for C4. It was on the arms industry and was likely to ruffle feathers. We – myself and another journalist and a small production company – pitched it to the commissioning editor at C4. He liked what he heard, agreed a budget and we made the programme – there really wasn’t much more to it than that. What was striking was the absence of crushing bureaucracy, of layers of management all wanting their say – and getting in the way.

From the outset, C4’s remit was to commission externally-made programmes. What this has meant, in 25 years, is the spawning of a whole new industry – one that is now a vital contributor to the UK economy.