All three leaders have set aside time tomorrow to prepare for Thursday’s broadcast on ITV, appointing colleagues to act as their opponents in sparring practice.

Brown has Alastair Campbell playing David Cameron and the former Downing Street adviser Theo Bertram as Nick Clegg. The Liberal Democrats are using David Laws as Cameron and Chris Huhne as Brown. Cameron has asked his shadow culture secretary, Jeremy Hunt, to spar as Clegg, Damian Green as Brown, and Michael Gove acting as the moderator.