The House of Lords has its defenders, despite being unelected and despite membership being for life. Its ranks include business leaders, scientists, medical professionals, civil servants, judges, military officers and others who might be put off running for elected office, but bring in a rich experience of life outside politics. They are not paid a salary, though they receive generous attendance allowances, so it is accepted that some will have paid outside employment.

Not any of this is an argument in favour of Lord Blencathra acting as a paid lobbyist for the Cayman Islands. He did not bring any great experience of the outside world into the legislature, because, as David Maclean, he was an MP from the age of 30 until he retired from the Commons, aged 57.

But he brought a vast experience of the inner workings of the British political system to the Caymans, one of the world's favourite tax havens. Almost uniquely, there are more businesses registered in the Caymans than there are inhabitants. Seventy per cent of the world's hedge funds are registered there. Its GDP is the 14th highest in the world.

It is also a British Overseas Territory, dependant on decisions made in Westminster to protect its idyllic way of life. Having an experienced political operator working for its interests inside the Houses of Parliament is obviously valuable for the islands. But it is of no value to the British public. If Lord Blencathra wants to supplement his generous MP's pension by lobbying for a tax haven, that is his right, but the question is, why he should be doing it from the privileged vantage of a seat in the Lords?

The rules which govern elected MPs are clear. They are not allowed to lobby for "reward or consideration" on behalf of any organisation with which they have a declared financial interest. That would clearly have covered some of Lord Blencathra's activities, such as lobbying the Chancellor George Osborne to reduce air passenger transport taxes on the Caymans, if he had still been an MP.

Such actions may not be against the current rules in the House of Lords, but they should be.