Thank you ton this is actualy my area of expertise.
From your account you were acting in self defence using reasonable force to protect yourself from a perceived imediate threat of violence .
Personally i would be reluctant to follow Juan's advise and report the matter to the police unless you can identify the bloke, as every crime report needs a resolution and they may decide you will do for the offender, cctv of incident plus you saying that big bloke using violence is me = charge of Affray, and it's up to you to raise self defence. A local Crime Solicitor will have a feel for how this would play out with your local police and weather or not it would be wise to get your account in early.
Should he get the Police involved do not talk to them without legal representation it is free at the police station and your lawyer will ensure you frame your account truthfully and with an eye to the legal issues . Do it yourself and you may find your account twisted to your disadvantage.
While i admire and understand your stance my advise is do not run the risk of further meetings vary your route that sort of muppett may well do something stupid and dangerous if he sees you again.