Virgin Flying Club is currently offering double miles (2 miles per £1) when you exchange your foreign currency at Amex Currency Exchange at Heathrow, Edinburgh or Birmingham. You can also get double miles at Gatwick at Moneycorp.
You can read full details of the offer here. It ends on May 31st.
This offer is particular interesting when you remember that Amex Currency Exchange charges Amex-issued credit and charge cards as a purchase.
This means that – if you use a Platinum, Gold, Green, BA, Nectar, SPG, Costco etc Amex card to pre-order your currency – you will earn miles or points on your American Express card. It will also count as spending towards any sign-up bonus you are working towards.
(Unfortunately, this does NOT work with MBNA or Lloyds-issued American Express cards.)
If you are flying through Heathrow, you can actually triple dip:
Earn 1 Avios per £1 or 2 Flying Club miles per £1 when you pre-order via Amex Currency Exchange
Earn 1 BAA WorldPoint for every £10 you exchange (show your card at collection, but they never post so keep your receipt and email or post it to WorldPoints)
Earn miles or points on the Amex card you use to pay