Happy to keep RogerB company !

[Mountain Goat]

Thanks.

Do they run on the same track? Is the track TT120 or the one Triang used?

[Too Tall]

The track is the same gauge, so you can run the modern rolling stock on the older track, and mostly vice-versa (old deep wheel flanges may cause some issues with some modern finer scale track).

Europe and to a lesser extent(?) America, have had TT120 for a long while so there are other track systems (Tillig being one, and looks to be what Hornby based their track system on) as well as Hornby and Peco in the UK.

My track is modern, mostly Tillig, with Hornby points, but if I were to do it again I would use Peco.