To be fair, isn’t Crossrail / Elizabeth line the first fully ‘digital railway’ in the world? Even Mark Wild basically came out and said too much was digitised.
Depends on what you mean by digital.
A electromagnetic relay is a digital device. A conventional relay has two states (* some specialist relays have three states, but they are still digital): energised and de-energised. It’s a binary digital device. Hence a route relay interlocking is a digital system.
If by digital, you mean computer controlled, as in computer based (that is there is still a human signaller that inputs each route), that describes the British Rail Solid State Interlocking (SSI) system (first full installation was at Leamington Spa in 1985). See
https://en.wikipedia.org/wiki/Solid_State_Interlocking.
BR then introduced Integrated Electronic Control Centre (IECC) systems (see
https://en.wikipedia.org/wiki/Integrated_Electronic_Control_Centre).
If you mean a computer based signalling system which has an automatic route setting (ARS) system, yet again, this is nothing new. That technology has been in use in this country for many years already.
In terms of train protection systems, we already have the Great Western Automatic Train Protection (ATP) system which uses digital computers and digital data transmissions. And we already have an ERTMS system. See
https://en.wikipedia.org/wiki/Europ...ystem_in_Great_Britain#Current_implementation
Digital describes a technology that generates, stores, and processes signals or data in terms of two states: typically represented by values of a physical quantity such as voltage (two different voltages or polarities such as positive and non-positive), magnetic polarization or physical position/state. One state is typically expressed or represented by the number 1, or logic high and the other by the number 0 or logic low. Thus, signals or data transmitted or stored with digital technology is normally expressed as a string of 0's and 1's.
Note that a digital signal does not have to have only two states, but it has to have a limited, fixed and defined number of states.