AtlanticMoose

Yes they send it back to the DVLA. I was given a photocopy of both sides of the card and the paper portion along with a yellow cc of the ontario licence application form.

a18ion

My experience was exchanging UK for Nova Scotia. No part 2 of UK license requested, just photocard. If they do send it to UK DVLA, it obviously doesn't work as I went on to UK Government Gateway and simply ordered replacement UK license sent to my UK address. As far as DVLA concerned, UK license active. Makes renewing UK passport easier, too, if you keep your photo current.

The rules are crazy, too. In Nova Scotia if you plan on staying for 90 days, you need NS license. In California, after 10 days of "residence" (we also reside there) you need CA license. So despite every place saying you can't have 2 licenses at the same time, it's a catch-22 situation, because each place requires one. So, we keep all three. Problem solved. If one of these agencies cares, they haven't said so.

christmasoompa

Although if it's not your actual address on there (i.e. where you're residing) that's not valid and a £1000 fine if caught. So don't actually drive on it whilst in the UK, even if it is useful for renewing your UK passport!

enak

I swapped my UK license in July for an Ontario one.

Until recently, if I used the "View my driving license information" link on the UK Government site it would tell me I had a valid UK license, but...
I can confirm that after 4 months, the message has changed from me having a valid UK license to "You do not hold a current GB driving licence, a licence has been issued by another licensing authority".

Hopefully that clarifies whether DVLA know anything. It may take a while, but the information comes their way.