On above cover Mahatma Gandhi stamp from Great Britain is used and it is a valid postage stamp before decimal system was introduce in 1972.
After looking other special cancellation issued during BPE in 1971 as well as other years I don't think that this is FAKE special Cancellation or just Rubber Stamp with Mahatma Gandhi Photo like we saw in 2009/2010 or any forgery like 1969 possible forgery.
The creator of this cover did excellent job by using Mahatma Gandhi stamp on this Special cancellation with India Study Circle and which make sense also. Think Different.!!
After looking at above link, all cover cachet and special cancellation were matching for all 4 days.!! I don't think I don't need to do research for this cancellation like I use to do for some suspicious cancellation.
Let us know what do you think.