One hundred and sixty-six — here’s the key” was the answer, but not to the question. I’d had the temerity to ask the Serjeant-at-Arms’s representative at the 1979 Commons’s Fresher’s Fair where I’d find my new office. “You won’t; not by yourself, for years. We’ll find you a desk space and a telephone, but not for at least six weeks. You can have a locker now. Try 166.” “Where’s that?” I inquired. “On the Principal Floor, probably down the Library corridor. You’ll find it.”

Finding the locker was, however, far from simple. I was very naive. I made the innocent error of believing that locker 166 might, just, be adjacent to locker 165 and 167. I’d been a Boy Scout, after all. I started my search for 166, and discovered that there were no rules. The numbering was entirely random: 122, 123, 124, 7, a, b, 109 was a typical sequence. I explained my plight in the Serjeant-at-Arms office. “Did no one tell you? Bombs. They moved all the lockers when the Commons got bombed in 1941. They’ve never been put back in order. Good luck.”

For days — literally — I’d scour the corridors. Then, about a week in, I suddenly saw 166, next to lockers “f” and “g” (how silly of me not to know). The key worked. I was a proper MP.

It was, on a practical level, infuriating. But I’m not sorry I had the experience. The search for a locker became a metaphor in my mind for the opaque mystery of Parliament, which remained my overriding perception of the place during the first few months and years. It still is characterised by quirky rituals, procedures and language. But in 1979 the Commons really was different.

For one thing, it was almost all male. Only 19 women were MPs in 1979 (3 per cent of the Commons) — compared with 127 (20 per cent) today. But it’s not just the composition of Parliament that has changed; even more so in the relationships between MPs, the press, and the public.

As Peter Riddell of The Times has observed, for 180 of the past 200 years “Parliament set the terms of the relationship” with the media. And how! Until the mid-1950s there were formal rules that banned discussion, on radio and television, of any issues coming up in either chamber over the following fortnight. This formal rule had broken down by the 1970s, but strong echoes of it continued.

The broadcast media were in Parliament on sufferance (with two tiny studios, in outbuildings). The parliamentary “lobby” — the select club of accredited political journalists — had a quasi-monopoly on political information, and therefore a common interest with MPs in observing the “rules of the game”; of which rule one was to maintain the mystery of the place, which only they could unlock.

That has changed dramatically in the 30 years since I was first elected. Parliament is now more open, and scrutiny of the executive is more intense. It’s just that, in line with T. S. Eliot’s rather dismal observation that “human kind cannot bear very much reality”, there is also much more scepticism and cynicism about MPs than there was when I first searched for locker No 166.

The huge paradox between the cynicism and the reality, however, is that Parliament has rarely in modern times been more effective at its job. This is down to three factors.

First, the decline in deference. Britain in the late 1970s was still very divided by class. MPs’ relationship with their constituents was often formal and distant. “Good constituency MPs” might visit their seats one day a month, if that. The constituency mail bag was a fifth or less what it is today. The expectations that the public rightly have of their public services — and of commercial organisations — are infinitely higher today than in the past; and so too are the demands on MPs when things go wrong.

The second factor has been the end of the Cold War. This defined British politics for 40 years. It was both the reason and the excuse for the climate of secrecy and non-accountability that pervaded every aspect of government. Neither the existence, nor the power, of the security and intelligence agencies was subject to any parliamentary authority whatsoever until 1984.

I worked as a special adviser in the mid-70s Labour Government, in the Health and Social Security and Environment departments. Routine submissions were classified as “confidential”. The days began with the ritual of safe opening. There were occasional leaks; but ministers in a corner could block many lines of inquiry by MPs and the media with impunity.

The third, and monumental, change in the past 30 years has been in technology. In 1979 there were no personal computers, no pagers or mobiles, no internet; no 24-hour news; just three terrestrial TV stations.

Routine sound broadcasts of Parliament had been established in 1968, with live coverage introduced in 1975. But radio itself requires the use of the imagination, and can help to reinforce mystery and mystique, while TV does the reverse. It was more than ten years after the introduction of live radio that the Commons was finally televised, in 1989. I voted for it then, and would do so again. But it coincided with, and probably helped to cause, a dramatic decline in newspaper reporting of Parliament and therefore in public understanding of democracy itself.

In 1979 The Times had 12 staff in the press gallery to give its readers balanced, quality summaries of debates and proceedings. But less than five years after the introduction of TV coverage The Times’s reporting of Parliament dropped to one tenth of what it had been. Today, as with the other broadsheet papers, it has no dedicated reporting of parliamentary proceedings. Of course one can watch BBC Parliament, or trawl endless websites to access Hansard, on the progress of Bills. But we tend to use the internet to search for “known unknowns”; while browsing in a good newspaper can introduce us to all sorts of “unknown unknowns”.

Parliament sat for longer and later in 1979 than it does now. But MPs are unquestionably more active today, at Westminster as well as in their constituencies, than they were, and hold government far more effectively to account, not least through select committees.

It was Margaret Thatcher’s first Leader of the Commons, Norman St John Stevas, who introduced the current system of departmental select committees the year I was first elected. In the decades since, their powers and practices have been greatly strengthened, while the Freedom of Information Act is producing a revolution in culture and attitudes in Whitehall.

I never dreamt when I was sworn in as a new MP 30 years ago that I’d spend my first 18 years on the opposition benches. But even if I had, I would still have volunteered for the life.

The British Parliament is a remarkable institution. It is a privilege to be part of it. As for locker 166, I rediscovered it the other day. Like much else, it had been “modernised”. It is now to be found, in sequence, next to 165.

Times Recommends

• We have kit and leadership. Let’s go
• Behind the scenes at the biggest deal
• Conferences — what a waste of money