However they are also allow for remote monitoring by CCTV; aside for stations where there are multiple gatelines and one or more are unstaffed, I'm not aware of places on the national network where this happens (but I've not been everywhere!), although it's quite commonplace on LU.
St Albans has a gateline controlled by CCTV.
Welwyn Garden City now uses CCTV and monitors to cover the lifts, which would allow people to bypass the gates to get to platform level or vice versa. At present, they don't appear to use it to control the gates on two individual platform islands from one place - but I don't go there often enough to know that for sure.