Tesco points at Esso filling stations

Went to my local Esso petrol station tonight for fuel and they asked me if I had got a Tesco Club Card for points. I was astonished.  Hadn't been in for a few weeks as we have been away on holiday.  They thell me they have been giving Tesco points now for about three weeks.

The question is: Is it just my local Esso that is doing this or is it all Esso petrol stations?  I didn't think to ask them.  I know there are folk on here who collect Tesco points and trade the vouchers in for part payment for Eurotunnel tickets.  I think they triple the value for Eurotunnel.  In other words £10 of Tesco vouchers = £30 off a Eurotunnel ticket.

If Esso are rolling this out nationally, it would be another good way of collecting the precious Tesco points for Euro-tickets?  Anyone heard of other Esso's doing this, or are we unique here?

David