A smart, searing thriller with blistering performances from McAvoy and Whitaker. Like the best Graham Greene script Graham Greene never wrote.

Whitaker's chilling, charismatic take on Uganda's General Idi Amin in The Last King Of Scotland stands up there with the great depictions of unhinged dictators like Antony Hopkins' Hitler in The Bunker or Christian Clavier in the 'Napoleon' mini-series.

Whitaker commands his scenes as effectively as he did in Clint Eastwood's film about Charlie Parker.

Whitaker is mesmeric as the bombastic despot, perfectly capturing his oddly comic but ultimately brutalistic ­nature.

So often the gentle giant, Whitaker changes tack here with an intimidating display of girth and guile, mixed in with the outward signals of untouchable nuttiness.

Whitaker is astounding in this role, moving easily between the happy charm that made Amin champion of his people, and the madness that led this infamous dictator to kill almost half a million of them.

It seems certain Whitaker will get that Oscar nod for superbly conveying Amin’s weird mix of buffoonery and cold-bloodedness.

Whitaker fully captures the menace of the man who murdered more than 300,000 of his fellow citizens, but also - and this is the difficult part - his humour, charm and charisma.