I'd have opened the N hand which we have to systemically open 1N, but partner passed it.
Opps 1♠ bid is Acol in a weak NT context, either he has 5 spades, or if he only has 4, he has at least 15 of the 16 remaining points and <4 hearts.
Opening lead is 10♠, opps are weak players who don't signal so no inferences can be drawn from which small spade E plays (in fact the 4), you win one of your high spades. Now what ?