Deputy Prime Minister Nick Clegg has cancelled a planned speech at the Oxford Union.
He was due to give a talk on 17 November but had to postpone it due to "an unfortunate scheduling problem", the union said.
It added the decision was not connected to Wednesday's students protest over tuition fees outside Parliament.
Two weeks ago Business Secretary Vince Cable pulled out of similar a visit to Oxford University over security fears.
A spokesman for the Oxford Union said they were informed last week that Mr Clegg would not be able to make it.
A statement said: "The Oxford Union regrets that Nick Clegg has postponed his talk, due to an unfortunate scheduling conflict.
"As deputy prime minister and one of the key figures in the coalition government, we are certain Mr Clegg would have shared a fascinating insight into current British politics with our members.
"We are sorry to hear that Mr Clegg will not be speaking at the union on the planned date and sincerely hope to arrange a alternative date soon."