From DVLA website:

"You only need to make a SORN for a vehicle that had a licence in force on or after 31 January 1998."

So you can have new V5 and not need Sorn.

And also:
"Vehicle keepers who have not received the new certificate and do not need to tax their vehicle, or make a SORN, by June 2005 and want one can do so by returning their V5 registration document to DVLA Swansea SA99 1BA with an accompanying letter.

From 1 July 2005 all existing V5 registration documents will no longer be valid. This will not affect entitlement to registration marks. Motorists who have a valid claim on a vehicle and its registration mark will not be disadvantaged. The V765 scheme which enables old vehicles to be re-united with their original registration marks, will be unaffected by these changes."