In reply to A Game of Chance: mebbe someone should tell the DVLA.
I've got a 'Renewal reminder to get a tax disc'
Which I can do at www.direct.gov.uk/taxdisc
And informs me that
"Your tax disc or SORN for your vehicle will run out on xxxx
You must either * tax your vehicle
* tell us you are keeping your vehicle off the road
* tell us you no longer have the vehicle"
And I can also
'Tax at a Post Office branch or by post'