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.
Aha, thanks for that mad_jock, down here we've been wondering what caused this:
Sea volcano blows its top 300km off NZ coast | Stuff.co.nz
Your post would nicely explain that. Any chance of giving us a heads-up next time FBW's out on the town?
FP.