Originally, there were five, now there are eight. The goats, as the Lords ministers from outside politics are known, are breeding. The appointment yesterday as Trade Minister of Mervyn Davies, one of the few senior bankers to emerge undamaged from the latest crisis, highlights how Gordon Brown has changed the balance of ministers and their relations with Parliament.

Back in June 2007, Mr Brown talked about a government of all the talents (hence the acronym) and looked outside politics for Baroness Vadera and Lords Jones of Birmingham, Malloch-Brown, Darzi of Denham and West of Spithead. Lord Jones has since stepped down, but the October reshuffle brought the creation of three new goats: Lords Mandelson, Carter of Barnes and Myners. And now we have Lord Davies.

Each of these has big departmental responsibilties. In the past, all but a handful of Lords ministers were primarily spokesmen, answering questions and doing the tricky and often arduous task of carrying through legislation, but with no real role in their departments. This began to change under Tony Blair, but it has been taken a big step farther by Mr Brown.

In part, this reflects a belief that there is not, if there ever was, the relevant experience in the Commons to handle demanding financial and business issues: a result, perhaps, of the rise of the full-time professional politician. So the goats are providing expertise not otherwise available among ministers, such as Lord Darzi at Health and Lord Carter covering the media, leaving aside the ex-City ministers.

But should the goats really be ministers as opposed to high-powered advisers? Mr Brown has seen them primarily as executives in their departmental roles, ignoring that they are also members of the Lords. Some have also been effective as parliamentarians, such as Lord Adonis, Lord Darzi — not least because he saved the life of a peer — and Lord Drayson, who became popular with the former defence chiefs of staff.

But while Lord Jones was an energetic trade ambassador for Britain, he was seen as less successful within the Lords. Lady Vadera’s added value is as a behind-the-scenes adviser and fixer for Mr Brown, rather than on the red benches or in interviews (as her failure yesterday to spot the green-shoots trap showed).

Does the growth of the unelected ministers matter? There is an accountability question. Lords ministers cannot appear on the floor of the Commons: yesterday, Lord Mandelson watched from the Peers’ Gallery as Ian Pearson, his junior minister, answered a question on business loans. But Lord Mandleson had appeared earlier before the Commons Business Select Committee.

The real lesson may be for MPs. Unless more of them have greater experience of the world outside politics, prime ministers will include more goats in their administrations. But political skills also matter and few goats have them.

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