Michael Brown: Voters have remembered Tories are rich grandees

When David Cameron reads this morning's latest ComRes survey it might cool his ardour for an immediate general election – and should make him less dismissive of proportional representation. These figures, which put the Tories at 30 per cent (down 15 points on last month) give them a mere 8 per cent lead over Labour – whose ratings are nevertheless similarly dire. With "others" on 30 per cent, these figures would result in a hung parliament.

The common assumption, up to now, has been that while all parties have been adversely affected by the scandal of the MPs' expenses revelations, the Tories have so far taken less of a hit than Labour – thanks to decisive leadership from Mr Cameron when contrasted to Gordon Brown's dithering regarding his own miscreants. But if our poll accurately reflects the current state of opinion after three weeks of this saga, it is clear that Mr Cameron's party has suffered every bit as badly as Labour.

The reason for this apparent dramatic slide in Tory support may simply be because, during the past 10 days it has been their MPs who have been the main casualties. Tory MPs have been falling like flies. Over a 48-hour period, before the Whitsun recess, Sir Peter Viggers, Anthony Steen, and a pair of Wintertons were followed by Andrew MacKay in announcing their intentions to stand down. Throughout last week the damaging media attention then focused on Julie Kirkbride. By the time Bill Cash (still surviving) was under the spotlight we barely noticed that another, Christopher Fraser, had also bitten the dust.

But it may be that the precise details of these scandals – wisteria clearing, moats, duck houses, manure and press photos of grand country houses involving huge gardening bills – have reminded voters that Tory MPs are still rich grandees who continue to live in a style "to the manor born". This could be seriously undermining Mr Cameron's painstaking efforts during the past four years to create a party that "looks more like the people it seeks to represent".

Our poll should also be a salutary reminder to the Tory high command that, under the vagaries of the first past the post system, they still have to achieve more than 40 per cent in the national vote and have a clear lead in excess of 9 per cent over Labour in order to secure an overall majority of one. As I have repeated on many past occasions, not only is proportional representation fair – it might actually be in the Tories' own self-interest.