an icepick through the keyhole

Providing your laptop fits into the new (small) sized bag, that can go with you. Regarding the guitar - that's another matter.

I flew back from Poland, through Gatwick, to Edinburgh on Sunday and watched as people flying out of Gatwick were told "One piece of luggage, this big" and two people had to check their guitars into the hold.

The Heathrow and BA websites have specific wording on this - all musical instruments into the hold even if you buy them an extra seat. If it's over the new size, and it ain't people, then it sits in the hold.

There is no indication that this particular regulation is going to relax anytime soon - says the man who was searched 4 times from Kraków to Edinburgh because his Kensinton Lock cable kept looking odd in scans.

I'd buy a really, really strong guitar case that wasn't too heavy and I'd also only put a travelling guitar in there.