The House of Lords’ involvement in the Brexit bill has brought the house into the full glare of public – and prime ministerial – attention, most recently because of Lord Heseltine’s vow to defy a three-line government whip. That interest will only increase with the behind-the-scenes BBC television series that began last night. Viewers who look beyond the red robes may recognise strong, honourable and spirited individuals working in the public interest. Many of us have striven to encourage a greater understanding of the vital constitutional role the House of Lords plays in the legislative process. I truly believe that if the Lords didn’t exist, something very like it would have to take its place.

The legitimacy of the Lords arises from its independent scrutiny of legislation. Occasionally members feel sufficiently strongly about an issue to push amendments but it is the House of Commons, rightly, that has the final say. We are not unaware of the somewhat arcane procedures in the current upper house and discuss them frequently. There is one question that gets particular attention: how many peers are needed to carry out this revising function? The short answer is: fewer.

In the past decade there have been numerous attempts to reform the House of Lords, including government and private members’ bills, committees, a standing reform group (long led by Lords Cormack and Norton), resolutions and any number of debates. Despite important incremental reforms, we as yet have no agreement on the ideal size of the house, the ideal recruitment mechanisms or a fair political balance. Two separate committees are now looking into numbers in the Lords, one chaired by MP Bernard Jenkin in the Commons, and the other chaired by Lord Burns in the Lords.

If the Lords is aiming to be a smaller, tighter, more professional and more effective legislative chamber, what needs to change? Although it is a full-time house, we do not necessarily need full-time members. The house is deeply respectful of those who bring current expertise to bear on draft legislation, whether that be in law, science, medicine, education, business or social policy. Part-time members who juggle a full-time professional career with parliamentary work are therefore invaluable.

There is also a small core of peers from all benches who, having achieved distinction in their careers, now devote themselves to parliamentary work – much of it unsung and all of it hugely in the public interest. An even smaller number of members attend only infrequently but nevertheless make a significant contribution because of their exceptional experience. All these peers spend hour after hour shaping legislation for the better. Their expertise, together with adequate time to debate and examine legislation, has caused the government to reconsider controversial policies.

And then there are those who attend faithfully, day in and day out, who use the facilities the house offers but make very little contribution other than voting during divisions. It is this last group that I have questioned. There is no rule requiring peers to attend for a certain proportion of any one day, nor is there any requirement other than signing an allowances claim form that parliamentary work has been “undertaken”. So peers who attend daily and claim allowances but contribute minimally break no rule, let alone any law. Sadly, however, this encourages the impression that we are a club rather than a legislative chamber.

We must challenge ourselves as peers and be honest when we know we are not doing enough. Perhaps we need to define “parliamentary work”, although a simpler solution would be fewer peers. A body of research suggests that the House of Lords could carry out its functions adequately with between 450 and 500 members. We currently have 805 eligible members. The reduction of the House of Lords by about a third (roughly 250 members) would have a profound effect on costs, without reducing the efficacy of the Lords’ work. Many hope this will be the recommendation of the two existing committees. Thereafter the challenge will come in the implementation, with some expressing concern that any recommendations might linger in the long grass.

I have consistently attempted to further this reform by pointing out publicly what many of us in the Lords have acknowledged and by encouraging peers, many of whom have given years of public service, to ask themselves a simple question: has the time come to retire? I, myself, have already committed to do so in the next parliament. Thereafter the task will be to move forward with a much smaller, and therefore more defensible, upper house.