I take it they're both mcalpine? Good sign of a decent manufacturer... Its the same as one I did in the week.
Is the rubber seal centred properly over the hole in the bath?
Is it fitted the correct way up ,some are not flat washers?
Well no wonder it leaks !! That area should have been smoothed off by manufacturer.
Out of curiosity ,on the underside of the waste hole in the bath ,is that area smoothed off ?
Unless you apply silicone ,or mait ,its unlikely that you will seal that overflow with just the washer.
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