So I have done another dummy booking right ahead in March next year, so no chance the BA codes are sold out in business, and this is what it shows (which explains why I missed it when booking):




To find out you are being shoved in economy you have to click the 'Flight details' downwards arrow (which I didn’t do when booking because I knew the flight details) and then it shows you this:



That is hardly making it obvious when booking that despite selecting Business Class you are in fact getting Economy on this aircraft!!!