Starting and electrical problem on a '97 X300 4.0

[fast cars]

Recently my Daimler Six 4.0 refuses to start from the key, instead a live needs to be given to a relay which engages the starter it she will run, the following have also stopped working at the same time;

Starter cranking from key (as above)
Wipers not working
NSF lights all nw
Speedo nw

All obvious fuses seem to be OK, can anyone point me in the right direction?

Thanks
D

[fast cars]

Thank you very much for both bits of info and advice, I will check both and see what happens.

Cheers
D