According to the JLR maintenance schedule, the Dynamic Response Valve Block filter should be changed at 5 years or 75k miles.

Bought the filter (outrageous price!) and the instructions to change look pretty simple.

Trouble is - I can't easily find a tool/socket to fit the shallow but very big hex head on the access plug so failed at step 1

Has anybody done this and can advise me which tool to buy?

This is a pic of the service instructions:

Click image to enlarge