Hi.
I've never heard of that TBH, any way of pointing to a link where it explains they are illegal.
I replaced the standard 21/5watt DRL/Sidelamp with approved LEDs within a week of buying the Panda, they were bought from a car bulb specialist (I can find the link later) they are no brighter than standard fitting LEDs used on the majority of other vehicles, but are better than the OE filament bulbs.
I also fitted LED number plate lamps I didn't want to fit ones that were too bright, in the main to take away the dull yellow looking effect from old bulbs, the ones I have now look exactly the same as on new BMW & Audis the snag though they are non canbus, so I had to fit a 22ohm 10 watt resistor in parallel with the bulbs, this is neatly epoxy glued to the inside of the boot door, the resistor only gets slightly warm and no canbus bulb warnings come up.
Incidentally, my Rover 75 had LEDs virtually all round (not headlamps though), insurance were notified and the MOT was passed each year with no issues, the only insurance stipulation was bulbs has to be certified with an E number, hard to find on eBay but the specialist companies sell them, hop this helps.
Here's a quote from a motoring guide which describes the situation more succinctly thank I can:
"1. New cars are fitted with LED lamps, why can I not install LED bulbs in my car’s lights to improve the looks and illumination?
New cars are fitted with LED lamps, which have been tested and pass Whole Vehicle Type Approval. Under British Road Vehicle Lighting Regulations, LEDs are not mentioned, because they were not invented, when the legislation was penned in 1989, meaning that they are not permitted at all. However, new cars fitted with LED lights are allowed to be used in the UK, because the lamps pass European / UNECE technical standards (although some of these latest LED lamps seem more dazzling to me than ever before).
Nonetheless, the ‘bulbs’ on those newer cars thus equipped, at the time of writing, cannot be renewed. If an LED module fails, the whole lamp has to be replaced.
Not only do conversion bulbs fail to comply with the aforementioned European technical standards but also fitting them ensures that your lamp will not perform as designed and will prejudice the Whole Vehicle Type Approval of your vehicle."
One of the main issues along with that above is Filament bulbs emit light in a different manner than led's. Normal lightbulbs give a even light output over the reflectors in the lights, which is what they are designed for. Light reflectors inside lamp units are not designed for LED's can have uneven lighting pattern, dead spots of low light and increase dazzle for oncoming drivers. (This isn't always the case but led bulb design is imperfect and combined with lights that are not designed for it means that you can never tell).
I think I would be very careful about led lights. Insurance companies make a big point (which legislation and the legal system supports) that it's your job to make sure all declarations are true and factual and by not doing so you could be in the deep end when it came to a claim. There was a case in the news a while back that a large insurance company - think it may have been aviva - disallowed someone's car insurance claim as it had a owners club sticker in the window that they didn't declare, as most insurance companies class any
stickers as "decals" and therefore a modification. If you look at any bulb manufacturers information page on led bulbs they say "for off road use only". That means they have declared that they shouldn't be used and the onus is on the user to check.
Dodgy led bulbs with E markings are still not legal and while I'm with you that you acted in good faith and you shouldn't have been misled, while the law may allow for a certain degree of "ignorance" (not calling you that, just using the term as a explanation), insurance companies do not do so and coupled with all of those bulbs on sale legitimately saying they can't be used on Road, I imagine they wouldn't allow the explanation from one advert saying they are ok to use when hundreds of others say don't do it, so a modification and one that's not legal for Road use would be a toxic mix that could land us in trouble.