Primus inter pares,or the First Among Equals.
In UK terms an elected dictator with authority on all matters related to British life except for defence spending and procurement - the latter being left entirely in the hands of the defence industry.
The office of PM has had some fine inhabitants over the years, such as Winston Churchill, Margaret Thatcher, Benjamin Disraeli and William Pitt. Unfortunately, it has also seen some utter wankers - chief among them the current incumbent (see Tony Bliar), his likely successor (Gordon Brown), that clown Major and any amount of insignificant losers.
I realise this isn't terribly incisive political analysis and comment, but I really just hate TCB. If current trends continue, a soon to be abolished position. Being replaced with El Presidente.