Mine ran out yesterday and I couldn't find the renewal letter (or the V5 - organised, me) Found the letter this morning and went to renew thinking at least I could do the monthly direct debit thing, but I didn't get the choice, just the old 6 months or 12 months. They're not going to send me a disc though.
I was flagged down by a policeman on foot for not displaying a disc once (it had literally just fallen off on the previous roundabout and was in the passenger foot well - he told me off and I didn't ask what he suggested I should have done given that I couldn't reach the disc from the drivers seat and I was parking in the first space I'd seen since it fell off. Different era.)