Both Cooper brothers sparred pastrano in London. Henry Cooper backed Erskine to beat pastrano on that basis and was proved right. I recon that tells me Cooper really fancied his chances against Pastrano because he must have felt Pastrano was easier to get to than Erskine was. I think Henry knew for pure boxing he could never out box Erskine himself where as Cooper clearly felt he could outbox Wiillie from their sparring session. His quote was "Erskine knows more about boxing than Pastrano ever will". I would back Henry, though not to knock Willie out.
I love this fight and see it close, Henry connects with enough force to make Willie hesitant to throw which would be the difference. Willie had the skill to win here but stunned several times would simply not throw enough to come out the winner.