Forest of Dean Branch Google Map
The map below shows the approximate routes of the Forest of Dean Branch from Bullo Pill to Cinderford, and to Drybrook Halt. A lot of the trackbed south of Cinderford appears to be recognisable, but industrial development to the northwest of Cinderford has made locating some of the Drybrook branch difficult, and I have had to make a guess based on a 1919 Ordnance Survey map.
The cyan line represents the line from Bullo Pill to Cinderford Town, the blue line is the branch from Bilson Junction to Drybrook, and the red line is the Churchway branch from Bilson to the site of Northern United Colliery.
Again, I'm not claiming this diagram to be 100% accurate, and no public rights of way should be inferred.
PP59 - Past and Present Vol 59 "Central Gloucestershire"
I've not shown the unused section north of Drybrook at the moment; I may have another look at this at a later date.