Similar to what was offered to the 737 guys employed in LGW through OSM. Certainly softens the blow slightly, and a useful little "bonus" to anyone based in LGW but living in €-land.
I believe the offer is the same amount, but a minimum amount of GBP guaranteed by setting a bottom-line exchange rate.
If (unlikely as it seems ) the € recovers that prevents a loss in the other direction for those whose life is conducted in € currency.