Castlefield Carnival was being held on May Bank Holiday. There were two bank holidays in May. One was on the 29th, the other was on May 8 which had been moved from May 1 to celebrate 50 years since V.E. Day.
Bill's birthday is March 23rd 1978 which makes the character an Aries.
John Simm was born on July 10 1970, a Cancerian almost 8 years older than the character.