Hi Glyn, thanks for your suggestions, useful as always – especially about the two men. I want to keep ‘heritage’, because that’s a very important part of the story. As to Ukraine, I’m sickened by Western leaders patting themselves on the back while the Ukrainian people try to resist a superior Russian military alone, and I don’t want to make use of what is going to be another terrible human tragedy. This is a personal choice which not everyone would agree with. What I have written into the text following mention of the triangle is this: 

And Katherine cannot resist the opportunity offered by her new Czech friends to join in risky covert resistance against a hard-line regime in place since the ‘brotherly assistance’ of the Warsaw Pact invasion.

I think most people will make the connections with both the aggressor and the pretense. There’s a lot of reference to Czechoslovakia ’68 and Hungary ’56 in current news reports.