loads of play in the lever (see the video) – popped off the plastic cap – adjusted the allen in there now the clutch doesn’t engage,

shifting was poor, like the mech was being forced, was having issues with smooth shifting into each cog

video

pic

You probably tightened the clutch too much. You’d probably need a half turn at the most. Try backing it off.

Don’t they all have play in the first bit of lever travel? Certainly my SLX/Zee/XT/XTR ones all did. I haven’t used 11spd Shimano though. That’s not a reason to adjust the cam. And yes, if you overdo the tightness the shifting suffers.

Just stripped an XT version yesterday, play in the lever until it engages is normal. Poor shifting on the one I stripped was down to the cage pivot (just visible as a hex under the clutch assy in yor pic) having seized. Slide the clutch off it’s shafts, and check the cage is able to move.

Had a fiddle with the Allen key for the clutch – clutch doesn’t engage at all now

The bad news is that your clutch cam unit is almost certainly broken (I’ve broken 3!). The good news is it’s a cheap part and you can buy it here:https://www.bike-components.de/en/Shimano/Cam-Unit-for-RD-M820-RD-M786-RD-M675-RD-M640-RD-M615-p38237/

Pull the part out and have a look.

Thanks

Is that part the same for all units as I can not find a off of the Rd-9050 exploded diagram

Same part. The new M8000 may be different but it’s correct for yours .