Report the faulty light to the Council concerned or to the Police with the exact location and dates when noticed. (You might decide to withhold your details - or not) Did you do that ?
(Best to always seek out professional legal advice - I am not a lawyer and cannot advise you).
(Somerset Council show on their site how to do this - the fact that they do one may conclude means that they do have this happen so the likelihood of failure is not only possible but 'expected')
here.
The Box above the Traffic Lights is the sensor and are vehicle-actuated (VA) which are fitted with microwave detectors - the boxes mounted above (usually) the signal heads. They won't activate if a vehicle is lower than 10mph and within 5-40m, so if the sensors are mis-aligned they may become 'stuck'. Some are 'light activated' but I cannot tell which is which.
If you cannot see any CCTV or Red light cameras (rare on temporary lights) then I doubt you will have activated any legal actions against you.
Whilst there is something about whena light is faulty you may proceed with extreme caution I cannot find the relevant section. I will keep looking.
North West Evening Mail - News -
Faulty traffic lights spark safety fears - Published at 13:21, Monday, 01 August 2011 - Lights on the A5093 at the Oaks near Millom.
DfT Apr 09-
Integration of Pedestrian Traffic Signal Control within SCOOT-UTC SystemsThe Register (Red Light Priority for Peds)Surrey University study on Traffic Lights see
here.)