Last week’s TV dramatisation of the fall of Margaret Thatcher, ‘Margaret’ (BBC2 Tues 26 Feb) was, despite a stellar cast, dubious entertainment. I suspect many who watched it did so either because of their admiration for the then Mrs Thatcher or to revel in the speed and brutality of her downfall. Nobody in British politics has provoked such divided passions.

While ‘Margaret’ failed to shed new light on well documented events, it did remind us  both how much and how little things have changed in the nearly 20 years since Ken Clarke booked the van for M & D Thatcher’s removal to Dulwich.

Some things never change. When a leader, no matter how revered, becomes a liability, it doesn’t take long for plotting to gather pace. Also the person who strikes at the leader must make the initial blow fatal if they are to ascend to the leadership. Two things are different now. These days Conservative leadership seems to shop at Cotswold Outdoor rather than in Savile Row, and, inconveniently, their party members get a vote. That makes a Westminster coup of the sort that brought Margaret Thatcher to power almost impossible.

Now Gordon Brown’s ‘second bounce’ has deflated and the Conservative lead in the polls has again grown speculation about his successor as Labour leader has inevitably followed. This time nobody serious is suggesting that a change of leader before the election is a real prospect.

Labour has always been ludicrously deferential to its leaders. The Conservatives have, by one means or other, ditched four of its ten former post-war leaders. Four more resigned immediately after electoral defeat. In the same period Labour leaders who have avoided dying with their boots on had either the luxury of retirement or did the decent thing after the polls had closed. Jim Callaghan even stayed on for nearly 18 months following his defeat by Mrs Thatcher in 1979.

Were Gordon Brown to win the next election few would imagine he would lead Labour into another contest but were he to lose there is no guarantee he would fall go immediately.

Anyone looking to place a bet on Labour’s succession might as well draw a name out of a hat.

At this stage this is all we probably know about the Labour’s next leader. It will almost certainly be someone who behaves with total loyalty to Mr Brown’s government. Disloyalty or anything that looks like it will virtually rule them out of a future contest. He or she will seem personable and likable rather than dour and serious. Politicians chosen by members tend to be a knee jerk reaction to the persona of their predecessors. Don’t put money on a Scot.

At present the bookies make Harriet Harman favourite. Most Labour members would tell you that this unlikely, but the odds do reflect a deep-rooted desire. Rightly or wrongly, and it hasn’t always been reflected in the ballot box, Labour sees itself as a party that is ‘for women’. The fact of a Conservative as the first woman Prime Minister irritated Labour members almost as much as Margaret Thatcher’s politics. If a credible woman could emerge for a further Labour leadership contest she would have a significant advantage.

At present no Labour MP with serious leadership ambitions will want to be seen as a contender. Those who the media have so far speculated could become leader probably won’t. Between now and Mr Brown’s resignation some event – a parliamentary performance, a TV interview, a campaign debate, a conference speech – will mark out his successor. All we know right now is that it hasn’t happened yet.