Hi!

Driving along the road 40ish, suddenly the engine stops pulling - doesn't stall, just now power to move the car,
car slows down (obv) Pressing harder on the accelerator has no impact

Take foot off the "gas" and put it back on - whoosh no issue full power restored.

Got home, Reversing the car around, put it into park, got out the car and the brake lights were still on
Which is weird as my foot wasn't on the peddle (I was stood at the back of the car)

Anyone had similar?
Any ideas? 2013 L320 3.0 TD in grey! sometimes towing a Buccaneer Cruiser.

It's a drive by wire throttle so it's possible that it will get annoyed with throttle and brake being applied (or being sensed anyway) for a period. You can rev it with the brakes applied (a torque converter stall test, for example) but it will get bored of that after a short period and back off the throttle. 2012 SDV6 - it's missing a couple of cylinders
2008 TDV8 - it was a labour of love and is much missed

That sounds quite possible,

Got a new brake light switch on the way - hopefully that's it. 2013 L320 3.0 TD in grey! sometimes towing a Buccaneer Cruiser.