Actually it's on the Show Biz Blues 2CD "box". The second CD starts with two tracks from the Boston Tea Party and then continues with:
Radio 1 “In Concert”. Recorded at the Paris Cinema, Lower Regent Street, London. First broadcast April 19, 1970 (P) 1970 BBC
For more details, see:
http://discog.fleetwoodmac.net/discog.php?pid=563
