Swapping down lights to LED.

The ones that we have in our house are all direct mains input, not dimmable but you can get ones that are mains and dimming for a price.
Each 50w light is now 7w and brighter than the originals but each has their own feed

A transformer produces AC, and if I read the markings on that one correctly, the output is AC. LEDs normally run on DC, although it may be possible to use AC, depending on the voltage (or it may just go bang). Also, LEDs are not less about voltage, but need the current to be controlled.

Are your 3w LEDs just bare LEDs, or are they LED bulbs?

This is what we are looking at.

I'd probably replace the transformer to an led rated one as I believe there are subtle differences.
I'd also not buy 6000k bulbs either, but that's a personal preference.

[EDIT]

Those bulbs are DC, that transformer is AC. So no, it won't work.

Even if it might have done, why risk it for a ten quid transformer?

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I've done this - 16 in the kitchen, loads of other around the house. You have 12v GU4/ MR16 bulbs. They run off a driver that steps 220v down to 12v. The alternative is GU10 bulbs that run at 220v so need no driver.

12v LED drivers are about £10 each, you'll normally need one for each bulb.

The alternative is to get a GU10 lamp holder for £1.50, 2 Wago blocks to connect to the holder to the existing wire £4.32 for 20, and a Wago junction box for £2.50. That's what I've done as the GU10 LEDs have a better reputation for reliability and there's no driver to fail in the future. It's simple to do, pull the driver through the ceiling hole if you don't have access from above, cut and strip the ends of the wire, join  using the Wago blocks, put the blocks in the box and push back through. Don't trust that there's nothing live because you've pulled the lighting breaker, much safer to switch the main breaker off.

If you don't feel happy doing it yourself, pay an electrician. It's an easy job that they'll have done hundreds of times and will do quicker than you.

If you're going with MR16 they need to be AC compatible e.g.

https://www.expertelectrical.co.uk/philips-master-value-mr16

Your driver should be fine for those.

Yes I'd just be swapping to 240v GU10 LEDs.
Very reliable and less to go wrong (no transformer).

Simple job.

Assuming the old lamps are the same fitting they are also 12v DC. Should be be a straight swap but you may need to swap the transformer as some LEDs will flicker with a transformer rather than an LED driver.

As above, apparently it’s quite hit and miss as to whether the lamps work with a 12v transformer according to my wholesaler. Better to switch to a gu10 lamp holder and get rid of the transformer and the crap MR fitting.
Only thing to bare in mind is as the actual downlight was originally for 12v lamps it maybe class 2 so not earthed and as you’d be putting 240v to it you need an Earth connection to it