Meanwhile... while everyone chatters on about caps on the 220, most
especially when it could be on the right 2...
There exists another 220 rarity, unknown to most collectors, *and*
experts... (seen below)
There's only 1 'acknowledged' copy of a cancel in a book on 220's
which essayk has mentioned, and an unused copy, which I own, shown
below... far rarer than the 220a or 220c, and easily in the class
with the 220b, however there has not, to date, been enough notoriety
on it to elevate it to the status it certainly is deserving of...