The wearing of a HV Vest and being within the fence line sends out the message that one is Railway staff.
In the cass of staff, there are certain requirements as to visibility of approaching trains which actually mean that staff on duty cannot access the lines at certain foot crossings.
Being within the fence line can result in a Driver assuming that you are a member of staff who is in a dnagerous or improper position, or is on the track without a Lookoutman or other visible means of protection. This would result in the matter being reported to the Signalman, trains potentially being cautioned, and a visit from the nearest NR response unit.
The whole point of HV Clothing on the Railway is for the Driver to observe staff on the ground at a sufficient distance so as to be able to give an appropriate warning of the approaching train.
If you are taking a photograph then you should not be in such a position that you NEED to receive such a warning, and thus the wearing of HV clothing is of no use, indeed it is more likely to result in a visit by the NR response unit, BT Police, or even the Civil Police.
As an aside technically foot crossings are provided as a means to cross the line rather than as a place where one hangs about, in which case inside the fence line it technically becomes trespass.
You are far better off NOT wearing any form of HV clothing than doing so.
I never wear my gear in such situations, and thus the Drivers assume I am either a user waiting for them to pass, or observe that I am taking photos.
One should definitely NOT stand on any part of the actual foot crossing to take a photograph in case it gives the Driver any worries as to your intentions or your awareness, as this will almost definitely result in a visit from the BT / Civil Police, who may be less than responsive to you wanting to stay there.
