I think a load of ATCO's from Scottish were out sailing.
They must of had an Aberdonian with them with who got his wallet out, this caused a flux in the earths magnetic field. Although the chances of it happening twice in one day is pretty remote.
If one of them was bigger than the other that was proberly fisbangwallop getting his wallet out to pay over 4 quid for a pint, they usually have to NOTAM that cause it will take down the GPS signal.
That could all be bollocks and it was a sub going up to Faslane picking up its escort. Or it was the mine sweepers on exercise/ deguassing things.