I prefer to drive with the TSD switched off and particularly at night. However every time the car is started the display turns itself on again. Its a real pain continually having to turn it off manually maybe a dozen times a day. Is there a way to disable it from turning on at all until requested?

Pull the fuse?  Discovery 4 HSE
1998 110 TUM HS FFR Hard Top XD WOLF
1982 Series 3 Hard Top

*Gone:L462 D5 HSE LUX, L663 Defender 110 HSE, Discovery 3 HSE, 2014MY Range Rover Sport 5.0 Supercharged AB Dynamic; L405 Exec Vogue SE 4.4, 5.0 Supercharged Autobiography, Defender TDCi XS CSW, Defender TD5 HT, Vogue SE TDV8, Vogue TD6, RRSport SC 4.2V8, Classic 3.9 Vogue Auto, Land Rover Series 3 SWB

Just press the voice control and say "display off" if only the Mrs was so easy to operate

Yes, the best way to do it, is via the voice command.

I also like to use it off at night, it's too bright....
The newer cars (2010+) have a quick button to turn them off, I think. I remember seeing a button to do that, I think it's the one that replaced the audio settings.