Have put the 27 July Cambridge lunchtime event in the diary. There is a Cambridge gov site with a map that shows Christ's Pieces.
Look at: www.cambridge.gov.uk/leisure/mapblack.htm
Yes it really is mapblack, not mapblock, even though the map has some colour on it, must be the logic of a govenment department.
All totally irrelevant, the main point is GO ALONG IT WILL BE GREAT