The Manual and Sports Mode lights flash once car goes into Reverse and stays flashing unless you switch the engine off and turn back on. If you don’t car goes into limp mode. Only have this problem if you go into reverse. When you go into reverse there is a clonk in the gear box. This is an automatic gear box.

 

What kind of car? Year, model, milage.
I think old Discos have a common problem with the reverse switch. Needs a new switch. Once you get to it, the replacement is straight forward.
Usually people do the job from the top, by removing the center console, hand brake etc, and opening the floor panel by removing rivets. A moderate PITA.
Some successfully do it from under, but I heard it's tricky.

 

Sorry it’s y reg Land Rover discovery series 2 188 thousand miles on the clock

 

Y reg = 2001

I have a 2001 also. I notice the flashing M&S more when my wife drives my Disco. She slams the gears into reverse right after starting the truck and the flashing M&S pops up.
I keep telling her to slow down. It's an old truck. Start the Disco, let engine warm up, watch the RPMs drop to about 700 then slowly put the Disco into gear.
No problem after doing that.