Hello RangeRover !
To the No. 4 : a good friend has also an Long Branch No.4 with no visible markings. The only markings are under the forestock on the barrel. It was all original we bought it direct from the RAF Arsenal.
To the No1. : Sometimes you can find the broad arrow on different parts. It was not unusual to have this marking 2- or 3 times on one rifle and only one on an other. But i couldnt tell you that this one was combined at FTR.
Pictures where helpful.
Gunner