Probably not enough room for an impact driver  .
Experience is the only genuine knowledge, but as time passes, I have forgotten more than I can remember
Volvo V70 P2 2006 2.4 Petrol 170bhp Estate SE
MG Midget Mk1 1962

Previous: L322 Range Rover TDV8 3.6 2008; L322 Range Rover TD6 3.0 2002; P38A Range Rover V8 1999

agree, but groove will give chisel more purchase to start, hopefully.

Thanks Guys, Struggled with the impact driver & have contemplated the Torx method. I have however just spoken to a JLR technician & he went oh those little .

Apparently they always struggle with these, both trying to remove them & then trying to refill the diff due to the small hole. Good news though, he may be able to obtain the plug.

Well No luck in removing the fill plug (Totally seized). Tried a chisel, over sized torx the lot but no joy.
Then went to plan B & filled through the breather.
I had anticipated this scenario & purchased a 150 ml syringe, took a while but got the correct amount in. Obviously hadn't been changed for a long, long time considering the mud coloured oil that I removed.

On to the Front diff, then the gearbox, engine oil etc. etc