Many thanks all who reminded me about the Perry figures,(Helen & Jericho) I'd forgotten about them - I'm assuming they're the standard Perry size (that is, smaller than WG 'heroic') & so should fit the WG & Rubicon 251s without, like the WG/Italeri plastic ones that come with their 251, looking like children compared to the standard figures. Thanks TT, Vodkafan & aphillathehun , I'll check out the BTD, victory force & JTFM ones too.
Has anyone used the mid/late war pewter ones from WG? (pic below) they're not bad, but the problem with 251 kits in 1/56 is that there's generally only room for a few of the models to have feet (oddly, though the Rubicon offering is very slightly smaller than the WG, it's cab has more room in it).