Some pollsters already speculate that such a lead would drive some former Tory voters, if not back to the Tories, at least to the Liberal Democrats. The assumption is that the electors will suddenly take fright at the prospect. Aren't those just the circumstances in which old Labour will rear its head again? And wouldn't a Blair government with such a majority become a sort of tribal, triumphalist, five-year-long version of Neil Kinnock's infamous Sheffield rally in 1992?
Probably not. Yes, governments that make a big difference almost invariably have equally big majorities: The Liberal government of 1906, Attlee's of 1945 and mid-administration Thatcher all had majorities well in excess of 100. You have only to consider the the big privatisations. Almost all were deeply unpopular before they happened, which is partly why there was so little about them in the 1979 manifesto. Yet while Mrs Thatcher's all went through, John Major was unable to privatise the Post Office - despite backing from left to right in the Cabinet - because he couldn't be sure of a parliamentary majority. If, for example, Tony Blair and Gordon Brown were to introduce far-reaching welfare reforms then it would be as helpful to them to have a big majority as it was to Lloyd George in his transforming 1909 budget.
But that does not mean that with a landslide majority Labour simply returns to its bad old ways - or even that the chances of a new, more pluralistic politics are out of the window. All the calculations are that the one member, one vote system of choosing candidates, Blair's own leadership and the growth of political education within the party will lead to one outcome: the bigger the Labour majority, the more Blairites there will be in parliament. Now let's take four potentially difficult issues likely to crop up in the first half of a new parliament:
Proportional representation: The conventional wisdom is that Labour would be more likely to back electoral reform if it has a narrow majority. Why change a system if it delivers spectacularly? But it may not be so simple. First, many MPs, finding themselves in hitherto natural Tory territory, may wonder how long they can remain MPs under the present system if the tide turns. What is more, if Labour secured a majority of more than 200 but with less than 50 per cent of the vote, the case for PR would be strengthened and made a much more respectable cause for Tories. Douglas Hurd, to name but one, has long been sympathetic. If others followed, it could be a huge help to the reformers in securing a vote for change in a referendum.
Northern Ireland: Blair is said to believe that John Major has squandered some of his well deserved early success - though Labour has been careful not to play party politics with the issue. But reviving peace will be a priority. Blair would be at least as tough in demanding an unequivocal ceasefire before admitting Sinn Fein to all party talks. But a landslide would deprive Ulster Unionists of their leverage to demand advance decommissioning of terrorist weapons, even if they were overtly allied, as they may be, to a post-Major, pro-Union Tory party.
Europe: There may be a pro-Europe majority in the House of Commons even if Labour wins only by a handful of seats. Not only the Liberal Democrats but a significant pro-European minority of Tory MPs, led by Kenneth Clarke, might well defy a three-line whip and vote with Labour to join a delayed or second-wave EMU. But it could be a close call, if Labour is running a minority government. Then you can not be sure that Labour Euro-sceptics will not outnumber the Tory pro-Europeans. A large majority gives Blair more freedom to negotiate a deal at the Inter-governmental conference in Amsterdam and it will make it much easier to get any EMU legislation through the Commons.
Scottish devolution: A landslide would make it much easier to get legislation through the Commons. Anti-devolution Labour MPs, such as Tam Dalyell, would have much less leverage to cause trouble. And Labour would be in a strong position to face down demands for the committee stage of its devolution Bills to be taken on the floor of the House. But a landslide would also mean good parliamentary majorities for England and Wales alone. Paradoxically, that also provides a ready made solution, if Blair wanted to take it, for the West Lothian question: exclude Scottish MPs from voting on business which applied only to England and Wales.
There are certainly disadvantages to a huge majority. Party discipline can be a casualty exactly because rebels can be heroes in safety: the government may win the votes, but at the expense of an awkward squad which tours the TV studios denouncing the leadership and damaging the party's popularity. The larger the majority the more competition there is for ministerial jobs. This can breed frustration among those who don't make it, so Blair would almost certainly have his new disciplinary procedure put to the test. On the other hand simply being on the winning side makes life more fulfilling for a backbencher: he has much better access to Cabinet ministers and can get things done for his constituency.
Margaret Thatcher could not possibly have got the poll tax through in the 1987 parliament if she had not had a big majority. However she forgot about the voters. So she won the battle and lost the war, by being unseated in 1990.
But that also illustrates the most important point - that a healthy majority makes it easier for Blair to put his own, rather than merely his party's, stamp on the country. A 1945 or 1906-style landslide is, if not utterly impossible, highly unlikely. But given where Labour is now, even a majority of 50 would be worthy of the term. And it would probably suit Blair almost as well. Robin Cook ran into flak for using the L word last week. Francis Pym went down in history for suggesting that it would be a good thing if Mrs Thatcher did not win too large a majority in 1983. No prizes for guessing who did himself more damage.Reuse content