Answer to one out of two questions

I have found the answer to my second question by reading posts on this forum and noting a link to search for No.19 Squadron’s ORB for June 1942 on the National Archives site. There was a good account of the day’s mission on Ramrod 23 and that the squadron flew out of RAF Harrowbeer.

I am still looking for what squadron the Bostons were in and hence where they flew from?