It is fairly common for airlines to run promotions selling their Miles at a special discount – 20-25% is a pretty standard figure – so it is not so surprising to see that British Midland have just announced a special 20% bonus deal on all purchases.
However, during the Summer, Diamond Club Miles will be converted to Avios at a rate of one to one – and Avios cost more.
The standard price for 20,000 British Midland Miles is £255 – the same number of Avios would cost £335. That is a big discount already but if you add in the bonus 4,000 you will get by purchasing through the British Midland promotion, you are getting a very good deal indeed.
I doubt you will be able to get Avios at anywhere near this rate in the future. The promotion runs until 30th June.