Just to clarify the legal situation: removing the bright colour or covering it with tape or paint is referred to in law as "Manufacturing a Realistic Imitation Firearm" which is illegal unless the defence applies to you. In order for the defence to apply to you, for our purposes, the RIF must have been manufactured in order that it be used for airsoft. Neither the law nor the guidelines actually define what the legal test is for whether an RIF was manufactured for airsoft or not, but a photo of you using it at a UKARA registered site is without any doubt at all proof that you did in fact use it for airsoft and being a member of this forum before the deed was done proves interest in airsoft, so any potential prosecutor would be hard pressed to convince a jury that the intention to use the gun for airsoft was not present at the moment of manufacture (BTW this applies to anyone regardless of age: u18's cannot buy any AEG's 2-tone or RIF, but they can manufacture them legally).
None of that actually matters however, since the Association of Chief Police Officers stated that the VCRA, as it applies to us, is unenforcible, which is no doubt why there have been no even attempted prosecutions for de-two-toning AEG's. Just to be on the absolute safe side, you could take your two-tone to a skirmish at least once before you strip/paint it, but if i were you, i wouldn't bother. The law is an ass, but it is the law and we must abide by it. That does not mean however that we must make life more difficult for ourselves than it need be. You cannot buy an RIF without a defence and in your case you cannot get proof of a defence without a gun, so buy a two tone and strip it immediately.
As our sentencially challenged mate Duck says, Fairy Power Spray does work, you just have to also apply some elbow grease. Painting over two-tone is a far less satisfactory solution for several reasons: paint costs more than power spray; even if you use several coats of paint and varnish it will get scratched and obviously bright colours show up through even minute grazes, particularly against black, and look decidedly less than cool...
...which is important because looking cool is not only good for the soul in general, it is very good for moral, specifically when you're in a timed game and knowing that you are TDB and you are going to conquer and get some, etc is what is going to make the difference between your team stuck behind hard cover taking pointless pot shots at extreme range against enemy also behind hard cover, happy to run the clock down, and 2/3/4 of you leap frogging across the distance using minimal cover but suppressing the enemy with concentrated fire on their cover by those not moving so the mover/s do/es/n't get hit, who then take/s over firing as t/he/y hit/s the dirt, and so on until one of you pops round the enemy's cover and ends their participation (soldiering 101: Violence Of Action intimidates the enemy & starts with moral).
Plus a completely de-two-toned gun has more resale value than a painted over two-tone.
, make sure you wear matching camo as well so you really do blend in 
