Mr Red:
Where in the UK might St Petersberg be?

they was deliberately vague but there is no doubt it refers to the politically oriented even if there is no nationality stated or (& I can be the authority on that point) ............ implied.
It has been inferred though. And other than my words, I am not in control of that.

At the time you mentioned 'brinkmanship' St Petersburg (sp) hadn't been mentioned. Only those involved in the negotiations, UK & EU, can employ brinkmanship. St Petersburg is a non sequitur