X300 - No gears - Automatic transmission

1995 Jag, 103K, regularly serviced by local reputable dealer, drives beautifully until this afternoon.
My wife had gone shopping to the supermarket, got in the car, turned on the engine, put the car in Reverse, nothing happened.
Tried in D, 2, 3 the car won’t budge.
She called me, I did the same, nothing happened.
Checked the transmission oil level (as recommended, with engine running), level spot on, right colour.
No warning light/s came on.
Locked the car, left it on the supermarket car park.
Any suggestions, please?

Sounds like the linkage has broken. that would be a lot cheaper fix than a new transmission. ( I just paid $4700 to have the transmission in my XJ8 replaced.)

Martyn; if I’m right this is a standard XJ6 which had a ZF tranny electrically controlled. So could be a control module or harness/wire connection failure. If mechanical I understand these boxes were prone to a fatigue failure of the the primary clutch drum preventing the clutch from engaging also a loss of control pressure owing to an internal seal failure with the same result.
Griff