Cable’s aide Tessa Munt MP is also being investigated, following a complaint by Political Scrapbook that the members did not declare polling, which is thought to have cost thousands of pounds, in the register of member’s interests.
Oakeshott, who resigned his membership of the Liberal Democrat party he helped to found last month, paid for polling in both Munt and Cable’s constituencies to gauge attitudes towards the party. The polls led to calls for leader Nick Clegg to resign.
The commissioner will now decide if the MPs should have declared the polls. Cable said yesterday he will cooperate fully with the probe.