A campaign group has set out a plan involving an amendment to the finance bill which would be conditional on a second referendum NIKLAS HALLE'N/GETTY

Supporters of a second Brexit referendum could curtail the government’s power to collect taxes unless Theresa May bows to their demand.

The proposal appears in a report on ways to force another vote by the Best for Britain campaign group. The report is backed by Dominic Grieve, the leading pro-EU Conservative, and includes advice from David Howarth, a professor of law at Cambridge.

It comes as Jeremy Corbyn urged the prime minister to cut short MPs’ Christmas break so that parliament can vote on her Brexit deal. Speaking to The Independent, the Labour leader accused Mrs May of trying to “run down the clock”. However Downing Street told the Press Association that it was a “silly demand”.

Under present laws, if Mrs May’s deal is…