The disclosure that the Blairs are buying a house in London will inevitably fuel speculation that the Prime Minister is actively planning his exit from Downing Street after the election.
Mr Blair tried to scotch rumours that he intended to hand over the premiership to Gordon Brown after John Prescott, the Deputy Prime Minister, spoke in the summer about the "[tectonic] plates moving".
Mr Blair this week again insisted he would serve a full term if elected a third time. But the purchase of a house in London will reopen the speculation that he is preparing to step down within a couple of years of the next general election.
The tensions between Mr Brown and Mr Blair over the Chancellor's ambitions to take over as Prime Minister resurfaced at this week's Labour Party conference. A senior minister said Mr Blair was worried about his bequest and Mr Brown was concerned about his inheritance.
The Tory leader, Michael Howard, who will host his party's annual conference next week in Bournemouth, will exploit the doubts about Mr Blair's future by running a general election campaign based on the warning that if the electorate vote for Mr Blair, they will get Mr Brown in No 10.
Also, the purchase of the house in central London could allow the Blairs to move out of Downing Street while Mr Blair remains Prime Minister, providing adequate security can be guaranteed for the property in Connaught Square.
Cherie Blair said in her recent book that one of the most dramatic changes on entering Downing Street for successive leaders was the lack of privacy.
"Time and again, in the interviews we did, there was a feeling that family life was sacrificed to the machine," she said. Mrs Blair also complained that the children were expected to play in a small patch of the garden at the back of No 10.