I did the service of the locking mechanism, cleaned and re-greased but it was still playing up so ended up replacing the steering column and problem is fixed.
My tip for this job is to take the top cowling cover off the steering column first to release the bottom cover.. that one really made me mad trying to get it off
Also if your steering column is locked straight you can drop the steering column by releasing the four bolts to access the pinch bolt a little easier.
A ratchet torx spanner for the pinch bolt that holds the column in is a must, it is virtually impossible without some sort of ratchet tool. I managed with a ratchet and torx socket at first but ended up buying a ratchet torx spanner kit which makes life easier again.
Steering wheel can stay on to remove the column if you are just wanting to try servicing the locking mechanism but ultimately needs to come off if you are replacing the column.
I did want to try the ELV emulator which does not require removal of the steering column but my wife was not keen on it
