Radio 4, as you may have noticed, is 40 years old today. It celebrates itself tonight with two programmes, 4 at Forty and Radio 4, This Is Your Life. There are two new books out, by the academic David Hendy and the documentary-maker Simon Elmes; and, to mark this birthday and those of Radios 1, 2 and 3, there is a 16-page supplement in Radio Times.

Does Radio 4 merit such a fanfare? Since the days of the Home Service, I have chosen to listen to it almost every day of my life, so honesty compels me to say yes – or, like Carlsberg, probably. What an audio A list it is: The Archers, Desert Island Discs, Today, Just a Minute, all those books, plays and serials, the sceptr’d'isle shipping mantra of Dogger, Fisher, German Bight. Yet, as I have grown older, I have become increasingly conscious of what it does not have, as well as what it does.

When was the last time, for example, that you heard on Radio 4 a real debate about leaving the European Union and repealing the Human Rights Act, to enable us both to deport foreigners convicted of murder and to reclaim our squandered sovereignty? When was the last time you heard anyone express the view that homosexual practice (as opposed to orientation) is undesirable or sinful, which is broadly the position held by the world’s three great monotheistic religions, if not the metropolitan elite that holds sway at the BBC? Have you ever heard anything at all, fictional or nonfictional, in favour of capital punishment? Moving along the traditional spectrum, when was the last Radio 4 debate on republicanism, or the last one about legalising drugs, and their true, as opposed to claimed, dangers? My own answers, since these are not rhetorical questions, would be, respectively: never; in October 1996, when Anne Atkins delivered her famously outspoken Thought for the Day; once, in March 2005, when a woman reporter on From Our Own Correspondent described the hanging of a child-killer in Iran and concluded by saying that for her it “somehow felt awkwardly, disturbingly right”; never; never.

Steadfast companion though it is, the problem with Radio 4 is partly that it has always sought to occupy the centre ground, which does not stay still; and partly that it reflects what Andrew Marr (a Radio 4 presenter) calls “an innate liberal bias inside the BBC”. Several others agree: Justin Webb, the Washington correspondent, laments the BBC’s tendency to “scorn and deride” America; Jeff Randall, ex-Sunday Times and ex-BBC, speaks in similar terms; Stephen Whittle, the BBC’s former controller of editorial policy, has criticised the corporation’s “monochrome thinking”. Most of this, incidentally, you can read on the BBC Trust’s own website.

“It is of the utmost importance that different points of view are given expression, without the heavy hand of BBC judgment . . . many of the assumptions about the boundaries of national consensus should be jettisoned . . . the parameters of ‘normality’ and ‘extremism’ have shifted.” These sharp words are not from any far-right pamphlet, but from From Seesaw to Wagon Wheel, an official BBC report on impartiality that was published three months ago, and a report yet to be fully implemented. Happy birthday, Radio 4 – but it’s time to leave the comfort zone.

Editor's choice

• The super cool Vampire Weekend
• Streep and Baldwin get complicated
• Guy Ritchie on Sherlock Holmes