The important thing to remember is that 'Airmiles' are completely different to 'Frequent Flyer Loyalty Schemes offered by the airlines.
Airmiles is changing, and soon to become part of the British Airways 'Avios' formerly Executive Club.
With the right kind of spending, you can benefit greatly from the Tesco/BA Miles scheme.
As a frequent flyer, points can be beneficial in a number of different ways.
I'm moving to Oman at the end of the week, and since i've got quite a lot of things to move, I'm using ba Miles to fly my dad out and Etihad Miles to fly him back to the UK so that he bring 3 x 23kg suitcases of my possessions. Taxes and fees in business is coming to about 180 quid all in all.
