CABINET Minister James Purnell was under pressure last night to explain why he claimed £10,000 more in Parliamentary expenses than he paid in rent for his London flat.

The Welfare and Pensions Secretary, tipped as a future leader of the Labour Party, pocketed £10,143 more than the rent he was being charged on his second home in London.

A Sunday Express investigation has revealed that Mr Purnell submitted rent claims of up to £2,020 each month – yet bank records prove that he paid only £910 every month…

On 17 of the 22 months he lived at the flat, he always claimed hundreds of pounds more than the rent he was actually paying. Records for the other months are missing…

A friend of Mr Purnell told the Sunday Express that [his then partner] Miss Walker often travelled abroad for her work and Mr Purnell would reimburse her in cash for a share of the rent and then claim that sum back from the taxpayer…

Mr Purnell’s explanation of his financial arrangements were branded “bizarre” by Liberal Democrat MP Norman Baker, who has campaigned for the rules to be tightened on MPs’ expenses, and “unbelievably complicated” by Liberal Democrat Treasury spokesman Vince Cable.

And Martin Bell, the former MP and anti-corruption campaigner, called on the Commons sleaze watchdog to look into the rent claims.

Putting the sums on a map helps show the patterns which are reasonable. And it also highlights those which are a bit more surprising, such as the previously mentioned Margaret Moran, Labour MP for Luton South who has claimed £80,000 more in expenses than another Labour MP living in the same street. She is the green blob in a sea of blue and purple just north of London.

The other one that particularly caught my eye was Conservative MP Chris Grayling, a frequent Conservative Party attack dog, who also stands out as a green blob in a sea of blue and purple – in his case, just south west of London.

The map doesn’t reveal everything by any means. For example, it doesn’t pick up the issue of Malcolm Rifkind (constituency: in London, location of Parliament: in London) claiming regular travel expenses for going back and forth between London and Scotland. But it is a useful extra perspective on what is and isn’t reasonable to claim.