quite simple really..
40 channel FM with a CB 27/81 circle/symbol..legal..Muppet, UK 40.
40 channel FM PR27GB square symbol..legal..New band, CEPT, Euro band.
80 channel FM PR27-94 square symbol 40 channel muppet and 40 EU/New band. legal.
Any CB's WITHOUT these symbols are ILLEGAL for USE in the UK..
if it has a CB 27/81 circle but is 80 channel it's also ILLEGAL as has been modified in a way as no longer conforms with the MPT specifications.
so any multi banded AM, SSB radio are ILLEGAL for UK use.
also power on a legal rig is 4w anything over 4w is illegal. so the use of burners,linears,boots and other nicely named items are illegal to use on CB, the MAXIMUM limit is 4w..but these can be use legally on UK amateur bands..but you must hold a valid UK amateur licence to use one.
also beware or sellers selling rare rigs, or old rigs, a lot of these are old AM set's from the late 70's early 80's and are the old americam AM 40 channels, and are most certainly illegal..
you can tell this but reference to the FCC on the back ID plate, any reference to FCC is american and illegal.
so when buying, always make sure it is legal for UK use, but there are some exceptions, president lincolns,rangers,omegas etc which are 26mhz to 30mhz actually cover a legal amateur band (10 mtrs) and these are legal to use but ONLY on 10mtrs, 28 to 30mhz band and with the correct AMATEUR licence.
useing AMATEUR radios like Yaesu,Kenwood and Icom radio on UK CB is also illegal..
check the OfCom website for more info on whats legal and whats not..
also from the 1st of december 2006 it is no longer a requirement to have a lincence, CB is now licence FREE, but you still need to be within the laws and the rules OfCom lay down, all the above still applies..
If un sure, don't buy, or buy from a CB retailer like Knights or truck king hope this helps...if not email me, i'll try and help further..