If the unloved former wife of your son were to die in a road accident, a wreath and perhaps a few kinds word would normally be considered enough.

However, when Princess Diana died in a Parisian underpass, the fury of (some parts) of the country (stoked by the press) descended on the royals up in Balmoral for their summer hols.

They were viewed - by a vociforous minority, it has to be said - as cold rather than blue blooded and were accused of a disgraceful lack of feeling for the most famous woman in the world.

Director Stephen Frears, commanding a formidable array of British acting talent, looks at the looming crisis from the point of view of the Windsors, the fledgling Labour administration and the ordinary man in the street.

In the opening scenes, we are introduced to Sheen as Blair with Mirren as Elizabeth and, by virtue of well-observed tics and mannerisms, become utterly convinced it's the PM and her maj. These are not shallow impersonations.

Mirren, in particular, imbues Elizabeth with a wry intelligence, acid wit and a patrician distaste for the likes of Blair; the sort of person who would have to buy his own furniture.

However, it is the prime minister's job to reconnect the baying masses, gripped in a manic grief, with a monarch who regards the death as a private matter and not an opportunity for outward shows of emotion. She also wants to protect the princes.

Public opinion, rallied by the press, is openly criticising the lack of a flag at half mast over Buck House and the withdrawal of the royals behind the walls of their Scottish retreat.

They, in turn, regard the prospect of a public funeral with horror and are aghast at a "chorus line of soap stars and homosexuals" replacing heads of state at Westminster Abbey.

Peter Morgan's rich, acerbic script crackles with one-liners - Prince Philip's undisguised disdain for "hysterics carrying candles", or Alastair Campbell's gleeful opportunity to wind up the royals (we see him tucked up in his jim-jams, coining the phrase "People's Princess" within an hour of her death).

While crammed with terrific comedy dialogue, this also ventures an utterly believable version of events and does so in a manner that is both scrupulously fair yet unflinching in its portrayals.

One of the films of the year.

Tim Evans