Neil,
I disagree with this. Whilst there is a recognisably British mindset to the Federation, the Federation as a government is not a reflection of the British government (under Callaghan for the first three seasons, Thatcher for the 4th). In fact Callaghan's muddled government and its alliance with the Liberals is quite unlike the unified monobloc of Federation rule. Nor can I see anything substantially Thatcheresque in Servalan (though I can't recall when Thatcher came to lead the Conservative party - was it before or after B7 began its run?).
Margaret Thatcher became leader of the Conservative Party in 1975, a few years before B7 first appeared. While she only became Prime Minister in 1979, the same year as the second season (the very season that Servalan seized power as President!), she was seen in those previous four years as having what it took to get to Number 10. Indeed, I recall thrillers written in the 1970s, set a few years in the future, who referred to a female Prime Minister of the UK, a rather obvious reference to Thatcher.
When I first watched B7, as a nine year old, I made an automatic link between Servalan and Margaret Thatcher, both being strong, capable women, who would go far, a link strengthened by the latter's election victory in 1979, and her ruthlessness. I mentioned this to Jackie in Deliverance 98, who was very amused!
Murray