IT WAS the week in which Britain decided to allow its usually stiff upper lip to quiver a little with rage. But it was also a week which showed that years of playing their parts with deadpan faces has left London's Foreign Office mandarins a little lackingwhen it comes to acting out raw emotion on the diplomatic stage. The first public sign of histrionics came on Monday, when normally ultra-cautious British Ambassador to Beijing Sir Robin McLaren ''lashed out'' at China's attitude towards the talks. ''One really does question the sincerity of those people who spend all the time talking about sincerity,'' the veteran sinologist said, in perhaps the strongest words he has directed at Beijing during a 35-year diplomatic career. ''It is common Chinese practice always to say that anything they do is the responsibility of the other side.'' But the real performance came two days later, as British team leader Anthony Galsworthy emerged from another failed Joint Liaison Group (JLG) meeting set on starting a war of words. Mr Galsworthy has been through many fruitless JLG sessions and managed to put a brave face on the lack of results. This time, apparently after consulting Governor Chris Patten and senior figures in the Foreign Office, Mr Galsworthy chose to take the opposite approach, laying great stress on the failure to make more progress. It was a piece of pure theatre, in which Mr Galsworthy acted more like Mr Patten than the mandarin he is. ''Frankly, I'm as bamboozled as you,'' he said, when asked what was holding up the JLG. ''It is clear the Chinese side approached this meeting with the intention of allowing only minimal progress.'' There was even talk of the deadlines, normally an anathema. ''At this rate it will take about 100 years to complete our work.'' It appeared to be part of a carefully-calculated campaign to try to increase the pressure on Beijing ahead of this week's cabinet summit on Hongkong in London. The strategy included tough new demands at the negotiating table, with Britain asking for a role in the Special Administrative Region (SAR) Preparatory Committee that begins work in 1996, in the week its precursor, the ''second stove'' working group, wasformally established in Beijing. London reportedly also pressed China, during the fifth round of talks, to pledge the SAR government will be fully-elected in 2007, the earliest date under the Basic Law. Both demands so enraged Beijing they were leaked to Wen Wei Po, which furiously denounced them as ''ridiculous requests'' that challenged China's sovereignty, even comparing them to Britain's behaviour during the Opium Wars 150 years ago - an old favourite whenever Beijing feels under threat. BUT Mr Patten was unrepentant, tacitly confirming the two requests in an interview with a local paper. He knows only too well the demands never stood the slightest chance of making any headway. His advisers undoubtedly told him as much before the subject was raised at the negotiating table. However reasonable such requests may seem to a former politician, China's repeated insistence the post-1997 running of Hongkong is purely its internal affair, makes it impossible for Beijing to be seen to strike a deal with Britain over elections in 2007, or even the composition of the Preparatory Committee. That is why Britain's sudden raising of the two demands seemed to be more concerned with giving an appearance of acting tough. It was all part of a new strategy that, together with Mr Galsworthy's table-banging, succeeded in putting China on the defensive for the first time since talks began two months ago. For a change, it was Beijing responding to Britain's accusations, rather than the other way round, with Chinese JLG leader Guo Fengmin rebutting his British counterpart's comments. Other mainland officials were asking what Mr Patten and British Prime Minister John Major would be ''plotting'' at this week's cabinet summit. Britain's play-acting seemed to have some effect, with China allowing the pace to speed up at the seventh round of talks. But this could hardly disguise this ostensible new hard-line is largely a charade. This week's cabinet committee is expected to finally bury Mr Patten's past pledge that the electoral bill be put before Legco by July, and may not even set a new autumn deadline. While London may be trying to act tough in public, and even sometimes at the negotiating table, the British side is effectively giving ground by allowing the talks to drag on. Yet there is nothing better to disguise that fact than a few carefully-chosen fireworks, and that is what the Governor and his fellow performers have been engaged in over the past week.