Taxing new second hand car - V5 not yet available

[SpeedChampion]

I'm buying a second hand car but the private seller does not have the V5 as he is still waiting for the DVLA to process a paper V317 to remove a private plate.

All seems genuine and above board but how do I tax the car if the new V5 is not yet available by the date of collection? I will have details of the old V5 (but not the paper copy as it is posted back to the DVLA).

Presumably if we do not submit change of ownership to the DVLA on handover date (because we cannot because we do not have the new V5 ref), the seller's tax will still be live at collection date and so I could drive home on that?

If I submit a V62 before the new V5 is issued, there is a risk that I'll just confuse the DVLA further, and does that help to allow it to be taxed anyway?

I assume that I can't deduce the new V5 reference from the old one (are they totally different and not tied to the car)?

[Pica-Pica]

Just to emphasise, the DVLA is only concerned with a record of a change of registered keeper, and does not (and is not) concerned with ownership (changed or otherwise).

[SpeedChampion]

Yes, sorry, I should have referred to change of keeper in the previous question.

I am aware that when I hand over the cash I will be the owner. The headache is how we deal with updating the keeper at an appropriate point in time to allow it to be taxed.