I agree - it's usually payable on the day after you have definitively left your employment - not just your last 'working day' but after any holiday or other paid leave has finished too.
I got mine after my employers received my signed Compromise Agreement, although it was about the same time as my normal pay date, as I was paid up to the end of that month even though I had finished working during the first week of the month, together with a 3 month PILON payment.