Labour’s leader is to announce a levy targeting holiday homes during the party’s conference in Liverpool.

The tax would be based on the value of each property and “equivalent to double the current rate of council tax”, a Labour spokesman said.

The announcement will intensify the fears of higher earners already bearing the brunt of his economic plans, amid heightened talk in Westminster of a general election if Theresa May fails to secure a Brexit deal that can be approved by Parliament.

Dawn Butler, the shadow women and equalities secretary, drew controversy yesterday on the eve of the Labour conference when she appeared to praise the hard-Left Militant group for stating in the Eighties that it was “better to break the law than break the poor”.

One Labour MP said: “This shows how much the Labour Party has changed under Jeremy Corbyn’s leadership. Here we have a member of the shadow cabinet endorsing the Militant tendency … and backing public officials who break the law.”