It has been a quarter of a century since a hapless sports reporter from BBC Radio 4's On the Hour was given his own radio chat show by the BBC.

Two radio and five TV series, four specials, two books and one blockbusting movie later, Alan Partridge has an unrivalled place in the pantheon of British comedy. Excruciating and and enduring in equal measure, it's now hard to imagine a world without Alan, as Partridgisms such as 'Smell my cheese', 'Kiss my face' 'Cashback', 'Back of the net' and 'Ah-haaa' are seemingly now part of the national vernacular.

Over the past few years, Partridge has been seen on Sky in Mid Morning Matters, Alan Partridge: Welcome to the Places of My Life, Open Books with Martin Bryce and Alan Partridge's Scissored Isle; plus on the big screen in the 2013 feature film Alan Partridge: Alpha Papa.

However, Alan's spiritual home has always been the BBC - he even spent an entire TV series trying to get a new TV run commissioned by them.

To celebrate Alan's return to the broadcaster in 2018 (as the 'voice of Brexit', apparently), this retrospective documentary will look back at his journey from radio caricature to the award-winning study of pathos that he has become.

We will hear from the man behind the man himself, Steve Coogan, as well as the acclaimed team that created him 25 years ago.

That cohort of writers and performers, including Armando Iannucci, Patrick Marber, Peter Baynham, Stewart Lee, Rebecca Front, David Schneider and Doon Mackichan, have gone become some of the most celebrated and distinctive comic voices of their generation.

Through interviews and a wealth of never-before-seen archive footage, including improv sessions, rehearsals and unseen outtakes, a light will be shone on the genesis of Alan, who despite being pedantic, egotistic, rude and neurotic, is regularly voted among the greatest comedy creations of all time.

And we'll hear from writers and directors Neil and Rob Gibbons, who inherited the Partridge mantle and, alongside Coogan, have taken the character to new heights, while being faithful to the character.

Did we mention he knows a cracking owl sanctuary?

• Alan Partridge: Why, When, Where, How and Whom? BBC2, 9pm.