Contacted Classic Cars LEDs and this is their reply.
"Thank you for your email.
The question of LED upgrades and legality is a complex issue which is not made any clearer by the fact the regulations stem from the RVLA.
Generally LED conversions are not 100% road legal for external bulbs, though ours all show the correct output and beam patterns (which many don't) so are not normally picked up here by MOT testing and don't give glare to other road users. The recent changes to UK MOT law has banned HID conversion for headlamps and some inspectors are treating this as LED too though we are seeing passes. Other fittings may be OK for MOT purposes but this is at the discretion of the inspectors. The Road Vehicle Lighting Act (RVLA) gives some exemption to vehicles of certain ages but as the act does not specifically mention LEDs it cannot be inferred by their absence that they are legal for road use. As a result we are cautious and sell all our external LEDs on the basis of "Off Road Use" only. Many insurers are now becoming tolerant of them and allowing the use of good quality LEDs such as ours as they are CE marked and they see them as a big safety improvement. Changing to LED for external lighting is a vehicle modification that you need to advise your insurer of.
It's a grey area between safety and legality that we leave to customer choice. Our Terms and Conditions which are linked to on every page on our website and email footer cover this in detail. Internal LED conversions are 100% legal and are not covered by the RVLA.
External LED conversion is an area where the law has not kept pace with technology and there are many industry members lobbying for this to be changed. However there is the battle with the large vehicle manufacturers and the influence they have with the authorities due to tax revenues, who do not like their vehicles being open to the aftermarket. At present, and we believe unfairly, LEDs need to be approved in every single light unit they would be fitted to. As you can imagine, this is an impossible task.
The wattage referred to in the RVLA actually refers to the light output, not the load. It's another reason the legislation needs to be revisited and updated as it is seriously behind where the industry is with technology.
We've been looking at this for a couple of years. The result of our research and correspondence received from a number of sources is as follows:
LEDs used for headlamps as LED modules for example, are always approved in combination with the complete headlamp (Regulations Nos. 112, 113 and 123).According to the Department of Transport (DfT), the Road Vehicles Lighting Regulations 1989 do not mention more recent developments in alternative light sources at all, such as HIDs (or LEDs) and, according to the DfT, this means that, strictly, such light sources are not allowed under British law. Many people presume that, because something is not mentioned, it is allowed, which is incorrect. The date exemptions shown in Schedule 4 only apply to technology that was available at that time, being filament bulbs.
We've also checked with United Nations Economic Commission for Europe and they have advised that no type approval currently exists for any LED module in the EU despite what is claimed by some. We have seen LEDs available that are E marked but when you delve deeper they are only approved for Electromagnetic Interference UN Regulation No.10 Uniform provisions concerning the approval of vehicles with regard to electromagnetic compatibility. This does not make them legal for road use. There are working groups within UNECE looking at retrofit LEDs but no decisions have yet been made.
As far as we are aware, this is the full legal position for external vehicle LEDs which is why we state "off road use only". We are continuing to find an approval route but it will not be quick unless the various bodies decide to look carefully at the excellent products now available and the fact that the beam patterns and lighting are often better than older filament fittings and provide a safer motoring experience.
Please let us know if you need more detail?
Kind regards
Duncan"
Italics are mine.