Here is the law (I cant believe I'm doing this):
http://www.legislati...796/part/I/made
http://www.legislati...8/52/section/36
Simple as that. Cyclists must obey traffic lights. By law.
http://www.legislati...796/part/I/made
The Road Vehicles Regulations 1989 said:“Pedal cycle” A vehicle which is not constructed or adapted to be propelled by mechanical power and which is equipped with pedals, including an electrically-assisted pedal cycle prescribed for the purposes of section 189 of the Act and section 140 of the Road Traffic Regulation Act 1984.
http://www.legislati...8/52/section/36
Road Traffic Act 1988 said:36 Drivers to comply with traffic signs.
Where a traffic sign, being a sign—
(a)of the prescribed size, colour and type, or
(b)of another character authorised by the Secretary of State under the provisions in that behalf of the M1Road Traffic Regulation Act 1984,
has been lawfully placed on or near a road, a person driving or propelling a vehicle who fails to comply with the indication given by the sign is guilty of an offence.
Simple as that. Cyclists must obey traffic lights. By law.