M. J. Powell wrote:
Is it still illegal to install a TV in a car where the driver can see
the screen?

No that was repealed under the RTA of 1987(sec 2:6)

It is ok to install a tv in the front of a car in the UK so long as
it is mounted centrally between the sweep area of the window
wipers. They must have tea cup holders on both sides fitted
to keep to EU law.

Sets must be of EU approved design and the extra car tv license
obtained from the DVLA.

Hope this helps