William Hague has since promoted Lord Mackay of Ardbrecknish to Tory deputy leader in the Lords replace Lord Fraser, one of several peers who quit the frontbench on Thursday.

Lord Mackay still keeps the shadow constitutional affairs portfolio - only now, with Tory peers in mutiny against the party leadership, his job looks a lot harder.

He denies the Tories' Lords reform strategy is in tatters - or that the main outcome of the row over the sacking of Viscount Cranborne over his secret negotiations with Tony Blair is to have made it easier for the government to get its reforms through the upper house.

Lord Fraser: Lord Mackay's predecessor resigned as deputy leader in the Lords

"I don't actually see where, apart from Downing Street, the theory that this speeds up reform comes from," he told BBC News Online. "I don't believe it does."

He insists it is Labour's plans that should be seen as in disarray: "What the government have done is they've backed off their manifesto commitment, which was to abolish the hereditary peerage, full stop."

"They didn't say anything about keeping some for a while, or anything else."

He won't be drawn on whether William Hague was right to sack Lord Cranborne - "clearly, communications and confidence had broken down between the two" - and, he along with the entire frontbench Lords team, offered his own resignation to the Tory leader.

What is Lord Mackay's own view of the deal Lord Cranborne got sacked for cutting with Tony Blair?

"I would prefer to see a deal for stage two" - the yet-to-be decided reform programme the government will undertake once the hereditaries have been removed - "right now, so that we know where we're going," he says.

"But as far as the stage one deal is concerned, I think it was satisfactory as far as it went."

The Tories will not oppose that section of the reform bill - not published yet - which contains the "half-way House" proposals put forward by crossbench peers on Wednesday to temporarily keep 91 hereditary peers .

Viscount Cranborne: His sacking has led to mutiny on Tory benches in the Lords

But Lord Mackay reserves the right to cause "maximum mayhem" - his own description of the opposition's role - to other parts of the bill.

He also refuses to countenance the notion that the Tories' intentions of providing concerted opposition to Lords reform have been set back in any significant way.

"I think we always tend to over-dramatise a day's events on the day or two afterwards," he says. "I think next week the train will move on and we'll be back to worrying about tax harmonisation in Europe and things like that."

When asked if he doesn't have the slightest fear that the Conservative Party's grand plans for opposing the government's Lords reform have gone off half-cocked, Lord Mackay laughs. "Ah well, it hasn't gone terribly well, this is true," he admits.

"We should be able to say that the government has backed off, they've climbed down from words like 'House of Lords an affront to democracy' and so on, and they're conceding that the Lords - including the hereditaries - has a part to play in our constitutional arrangements, and I think that's a great success."

But, of course, it hasn't worked out that way.