Wednesday night offers two accounts of African exile - Heat of the Sun (ITV) , in which Trevor Eve plays a disgraced Scotland Yard detective posted to Kenya and In Exile (C4), a sit-com set in the St John's Wood bolt-hole of a toppled African dictator. Which is funnier? In Exile should have a clear advantage, as it is actually intended to be a comedy. Unfortunately it isn't a very good one, while Heat of the Sun, which I think is supposed to be serious, is studded with gleeful moments of hilarity. You get the impression that some of those involved in the production can see the whole thing's a hoot, and have smuggled out the odd message to that effect, but does Russell Lewis, the script-writer?

The prosecution would argue that he doesn't, and they are aided by the fact that the man has previous, as they say in Scotland Yard. As the creator of Ambassador he is responsible for one of the least plausible dramas currently on air - a confection of stale urgencies and cliched dialogue. What's more, a forensic study of his work reveals a psychological consistency of method - with the opening scenes in particular betraying a kind of terror that the audience might take the hero as ambiguous in any way. In Ambassador Pauline Collins was first seen assisting an old lady down some aeroplane steps. Here, Trevor Eve presents his moral credentials to the viewer by shooting a serial-killing paedophile, behaving with gentle firmness to a black pickpocket and intervening in the beating of a native barman, during which he dispatches three boorish drunks without even creasing his coat. He maintains his reserves of strong, silent heroism with the occasional top-up: winking amicably at servants, saving a child from a burning building and - one for the road, this - staring into an African sunset, murmuring "A man could lose himself in such a place, if he'd a mind to".

On the other hand, the defence would argue that no one could knowingly create a character like Chico de Ville without bursting out laughing over the typewriter. Chico arrives on screen in a palanquin carried by native bearers. He has bottle-blond locks and a hello-big-boy manner that makes Julian Clary look like a closet case. Chico would actually be thought excessive in a San Francisco bath-house, but the robust young planters of pre-war Nairobi, otherwise keen to give physical expression to their inherited prejudices, appear to have decided that he's not worth beating up. Alternatively they may just be incapable - because the entire colony is in a state of permanent intoxication. One female character appears occasionally like a running joke, staggering through the background until she finally falls into a swimming pool during a dramatic moment of revelation. That last scene raised again the possibility that the whole thing might be intentionally funny - a kind of affectionate pastiche of genre stereotypes (including the lovely yellow biplane from The English Patient and the sinister eye-patched Germanic villain from Raiders of the Lost Ark. But if so, they really need to be a little more up-front with the comedy.

The same is true of In Exile, which has an excellent premise for a sit- com - the sudden reversal of fortune which follows a coup - but then does very little with it. Tunde Babalola's script betrays some clumsinesses of inexperience ("Oh, he's the chap that removed you from office and took over as President for life" is not a line that any actor could utter with conviction) and a willingness to settle for abuse, where wit would have been preferable (although one of the bigger laughs in last night's episode came for the line "Well, the Prime Minister is an arse", so one can see the temptation not to bother). There are glimpses of something better - in the direction of surreal invention (two stony Special Branch detectives perking up when General Mukata's driver reveals that he really wants to train as a dancer) and character comedy: "I do not need coaching" snaps Mukata when being prepared for an interview with Jeremy Paxman, "you are asking the wrong questions". That mismatch between old habits and new circumstances is what the comedy should really be about.