Bru, if you'd been 'nabbed' not only would it have cost you the duty, VAT etc., but they would almost certainly have confiscated the guitar as contraband. I worked in the shipping industry for 17 years, and I've seen the Customs guys in action many, many times. They don't fuck about.

DO NOT SMUGGLE, IT'S A DANGEROUS GAME. (Yes, Im shouting!) :-) :-)

And I reckon a cost of 65 quid to get a several-thousand-pounds-worth of guitar from the US to the UK in perfect nick is so small a price as to make any idea of flying over there and paying for two seats back, then SMUGGLING IT IN, absolutely ridiculous! :-) :-)