Trews? Were you with a (Lowland) Scottish regiment, then, Malcolm?
... long socks ... hose tops! Get some in, Mate!
Even back in my day we used to encounter other armoured regiments on "scheme" wearing sensible clothing. Even the Life Guards (IIRC) used to wear polo necks under their coveralls. But for some perverse reason, "our lot"* wanted to continue the traditions of the Second World War (I may have mentioned before that our QM had in fact crossed the Rhine in 1945 in his Daimler Dingo). Although I noticed that by "Gulf War One", they had at last adopted brown T-shirts under their coveralls.
Happily, a lot of the things we were always trying to implement (as in "get approved") back in my time have now come to pass; decent boots, "regimental" T-shirts, helmets that you could actually run in (although the Para ones were OK in that regard) and so forth. Hopefully, the tools and test equipment is a lot better, too.
Meanwhile, at the BMH's we used to wear "barrack dress" (usually Trousers, Lightweight back in the day), with "shirts, hairy" and Jersey, Heavy Wool during winter months, covered by a white "Lab coat" when out on the Wards (as per the policy of DEME(A) at the time). Luckily, things were generally a bit more relaxed in warmer locations (such as Hong Kong). No shorts in the hospitals, though!
* Mente et Manu