Cab Signalling CoActor

[Belperpete]

I noticed at Edgware Road, at the Paddington end of the Wimbledon platform, a marker board, with an identical board labelled "CoActor". This CoActor board was mounted at identical height to the main board, just a foot or two from of it (I can't recall now which comes first). What is the purpose of this board? I thought the trains are running on cab signalling here - I couldn't see any indicator or signal associated with these boards. Does the driver have a CoActor display in the cab?

The boards are so close together, that I would have thought one would obscure the view of the other until the train was immediately adjacent.

 

[Dstock7080]

Sighting from a seated driver position.
Hold board CoActor ERD21B, is placed after Hold board ERD21A.
If operating in RM Restricted Manual the driver would need to identify the signal and read back the plate.

 

[Belperpete]

Sighting from a seated driver position.
Hold board CoActor ERD21B, is placed after Hold board ERD21A.
If operating in RM Restricted Manual the driver would need to identify the signal and read back the plate.

Thanks for that.