Ken Livingstone has been handing out a 'voucher' promising Londoners £1,000 off their tube, bus and rail fares if he wins the mayoral election.
Labour's candidate was on the campaign trail in Uxbridge, where he launched his transport manifesto.
He is promising that the average person will save £1,000 over the next four years under his leadership.
Mr Livingstone said: " I am saying to Londoners – keep hold of this voucher so that you have physical evidence of my promise to cut your fares. The voucher will be available online from today, but will only be valid if I am elected as Mayor on 3 May."