Brimful of the historic exploits of the Tartan Army on the boulevards, I headed to the centre of London to view another invading force - the Terracotta Army, some members of which are on loan to the British Museum for the next seven months.

Over 150,000 people have made bookings to see the warriors that protected the spirit of the first emperor of China, and the queues on Thursday were of historic proportions.

Only a handful of the 2200-year-old figures are on display, more a platoon than an army, but I doubt if people will be disappointed. Turning away, I made a mental note to book for the Tutankhamun exhibition at the Dome - sorry, the O2 Arena - which opens in November, only to discover that I am 60,001st in the list for that spectacular. It's more than 30 years since the ancient Egyptian treasures last came to the UK, and I have vague memories of the stir they caused, though they sparked more of an interest in Hammer horror than archaeology.

Since its transfer to new owners and mobile phone network sponsorship, the O2/Dome has risen like an embalmed mummy itself. Plans for a supercasino on the site have gone the way of Tilbury docks, but as a musical venue it has quickly established a reputation. There's a baby dome inside the arena for more intimate gigs, and no one is complaining about the transport links, which include a fast clipper from Waterloo pier.

One of my friends suggested that if all the treasures held in museums the length of the land had been gathered in the Dome for the year it was open, then it would have been a millennium building worth celebrating and a genuine historic exhibition.

Really, you don't need to be inside a museum for history to come biting around your ankles. Continuing down Whitehall towards Westminster, I came across some media colleagues filing out of Downing Street. Another sonorous briefing from Gordon Brown, I wondered? No, a momentous photo opportunity: Baroness Thatcher back at Number 10. Wha ...? At first I thought it was a case of life imitating cartoon because the Steve Bell strip has had Lady Thatch escaping from her secure unit and marching off under the delusion that she was Gordon Brown while muttering "British jobs for British workers". I tell you, Tony Blair wouldn't have got away with something as brazen as having Thatch round for afternoon tea.

A bit like foot-and-mouth, you just get round to thinking that Lady Thatcher has been eradicated and she pops up again on every front page. There she was in a glorious cerise embalming, I mean dress, with Brown at the front door. Who should invite whom in?

The Tories accused Brown of taking advantage of a frail and lonely old woman who is barely compos mentis, but Thatcher was having none of that. Her spokesman said she was "fully aware" of the political ramifications.

Brown has even taken to using his old foe's election-winning advertising agency Saatchi and Saatchi, who have severed their links with the eponymous brothers and the Tory party for which they produced the famous Labour Isn't Working ad in 1979. Their pitch for the Labour account - "Not flash, just Gordon" - does seem to capture the man with some piquancy.

Just who should be more outraged by this audacious tea party, the Labour party or the Conservatives, is a difficult one to judge, but swiping his enemy's branding is becoming something of a trademark of Brown's.

(Speaking of stealing your opponents' credentials, check the number of congratulations for the Scottish football team on the BBC website that come from England fans. Do you think they've done it to show us up with their magnanimity?) Later, Brown breezed in (and breezed out 10 minutes later) to the New Statesman summer party across the road in the Banqueting House. Proving cartoonists know things that we don't, Steve Bell's friend and rival Martin Rowson was outside pointing to the exact spot of the scaffold on which Charles I lost his head in 1649. If only he hadn't insisted on the divine right of kings, he wouldn't be history on the pavement. Come to think of it, if Tony Blair hadn't insisted on much the same thing, Brown wouldn't be inviting herself to afternoon tea at No 10 either.

Inside were several hundred people, which, the magazine's proprietor Geoffrey Robinson MP assured us, is a fraction of the readership. The Statesman, like Labour MPs, is in rude health these days. There was more bad news for David Cameron. Ali Miraj, the renegade A-list Tory candidate who resigned claiming Cameron was all spin and no substance - nothing to do with being refused a peerage - was doing the rounds at the party, giving his old boss a good slagging.

Poor Cameron: he has to pull off the trick of convincing his party he will honour Thatcher's legacy while trying to reassure the country that the Conservatives have outgrown her reputation for cruel economics and licensed greed. All this with snipers from his own side taking aim left and right. A historic task, you might say. Only when the cartoonists draw him inviting Tony Blair to tea in Downing Street will he know that he has changed his party for good.