I must admit that I do not know the actual source of the following but it is from a very reliable friend of mine who ‘published’ it in our Family History magazine quite some time ago.
Issue no. 2272 – Estab. 1862 Saturday 28th October 1905 Postage One Penny
Deceased Wife’s Sister
He: “I can’t understand why an Englishman always wants to marry his deceased wife’s sister”
She: “Why? I should have thought anyone could see. It saves him the bother of breaking in a new mother-in-law.”