I've read through but I don't think the test manual is specific on how the tail tells should be wired? If the device that the tail tell is for (dipped, main, fogs, ...) are relay driven then the tail tell can get lit from the switch / coil side or the feed to the device.

Wiring on the switch side is preferable as I wouldn't need to use wires rated suitably for the level of fusing on the circuit. The former would be a direct indication of whether the device had feed to it and so wouldn't light in the case of a blown fuse or failed relay.

I'm preferring the light on the switch side to reduce the required CSA of the wires and simplify the loom. I think this is ok isn't it?

Take it from the switch, it's alot simpler and easier.

Thanks, that was my preference too.

As long as the tell-tail lights when the switch is on then it'll pass. There's no specification for how that it achieved or requirementfor the tell-tail to indicate whether the actual light is working or not operate if a fuse/bul has blown. Keep it as simple as possible. Mine run from the switch.