I too have SORNed a cougar today - KGV. Actually she's been sitting there waiting for those sills, which are about 2 months overdue and I clean forgot about the tax. So when the DVLA sent me a letter telling me I must get an MOT before they would condescend to allow my direct debit to work, I thought 'Stuff You', they will nolonger get money for nothing as Dire Straits would have it.
However, they don't make that anywhere near as easy as taxing it or updating your direct debit. Its like they are only trying to push you into giving them money. Three hyperlinks for paying, none for SORNing, so I gave them 'what for' in my Feedback. I feel sure that will make a world of difference ( not ) and I feel much better now. My bank balance is anyway...