Mark Leftly: It's ridiculous that Miliband wasn't given time to form a Budget response

Westminster Outlook The newly trim 5:2 dieter George Osborne won't even risk a gin and slimline tonic on Budget day. The one time of the year when a minister can get smashed at the Despatch Box and there's party-pooping Austerity George sipping a mineral water.

Ken Clarke famously revelled in the Palace of Westminster tradition of allowing Chancellors to guzzle booze while delivering the Budget speech. The MP you'd most like to have a pint with would, for an hour or two, switch to whisky, while it was Thatcher-slayer Sir Geoffrey Howe who favoured G&T.

This little convention is one of those quirks of the British parliament that so delight political anoraks, the Westminster Bubble, and American tourists.

But the point is that a chancellor is not compelled to drink sherry and beaten egg (William Gladstone), milk and rum (Hugh Dalton), or even a straightforward brandy (Winston Churchill).

In 1997, Gordon Brown ditched the tatty red leather briefcase that every chancellor bar Jim Callaghan had used to carry the Budget for the previous 117 years, because it was falling apart and struggling to fulfil its basic task: holding documents. The reverend's son was another who refused a tipple when he unveiled his 11 Budgets.

Admittedly, it's not a particularly popular argument these days to suggest following the lead of our last unelected prime minister. But Mr Brown's refusal to adhere to preposterous traditions, no matter how charmingly quaint, should reach its logical conclusion: give the Opposition the Budget and the blasted speech several hours before they are delivered and published in the early afternoon.

Ed Miliband has been roundly criticised for failing to address the details of the Budget itself in his response on Wednesday, instead dishing up a generic cost of living counter-attacking speech that, as Nick Clegg pointed out, could have been delivered on any other day of the year.

But leaders of the Opposition face the plainly ridiculous task of responding to the most significant annual political set-piece almost completely unprepared. They must make an immediate response to a dense, policy-heavy set of announcements that can contain total surprises, such as Mr Osborne's remarkable overhaul of the pensions system.

The Budget turns into a virility test of thinking on your feet. Effective oral argument is a sign of quick-wittedness and, more often than not, high intelligence, yet it is seldom the best way of settling a debate.

Given his intellectual reputation, Mr Miliband might well have the ability to dissect the numbers of a Budget and tear a Chancellor's fiscal plans to shreds if only he had a morning of peace with the document.

It is, after all, Mr Miliband's job to hold the Government to account and make sure that the Chancellor's figures add up – he should not be hindered from doing so.