If you think Barack Obama has big, sticky-out ears — and he often jokes about that — then you ain’t seen nothing yet.

A series of grotesque modelled heads in a current exhibition offers ears of truly astonishing proportions; more suited to a bat than a human — and it’s all in the name of an artist paying homage to her African inspiration.

The heads — there are 15 of them — also boast thick fleshy lips, flattened noses and shaved or perhaps just bald skulls, are garishly painted, sometimes gilded and studded with glitzy beadwork and slips of coloured leather.

All very well made and beautifully presented, yet to me they look like sculpted versions of a 20-year-old painting by Kenya’s Kamal Shah, a man who never shies away from decorating his paintings; even at their best these ritzy, glitzy faces seem meretricious and look cheap.

Curiously the artist who made them, Lizzie Thurman, shares something else in common with Shah, as well as a penchant for gee-gaws — they both trained first in textiles. There must be something in the warp and weft of such studies that encourages brave excess.

I imagine these heads seemed like a good idea at the time, maybe when being moulded in papier mache far away in the rolling hills of the English countryside where they would appear exotic, reflecting the vibrancy of this continent.

Yet they left several African visitors I spoke to aghast and protesting that they are stereotypes; simply ugly caricatures.

I do not think for one minute that the stereotyping was deliberately offensive but rather the unfortunate by-product of a stereotypical vision; the work of an artist who failed to think round corners.

Surely no harm was intended — just the opposite in fact, for they are supposed to be an examination of “universal, social and cultural contradictions,” and are loosely based on the antique bronze heads from Ife seen by the artist in an Oxford museum.

They struck me as middle class versions of the paintings of Maasai you see in curio stalls; tall, razor thin, sometimes balanced on one leg against a spear and wearing long red togas; if animated and given bodies, they would probably leap up and down.

The Thurman heads were made by a non-African while the paintings are by Africans for mainly foreign consumption, which raises the proposition that while it is OK for a community to parody itself — also witness the exaggerated features of Africans found in cartoons by Africans (Gado, Maddo and so on) in the daily press — outsiders do so at their peril.

Mind you, cartoonists (and Michael Soi) tend to be fairly even handed about this. They dish it out in all directions.

Does it depend on who is creating and who is viewing to condemn the sort of stereotyping found in 1930s minstrel shows as offensive and embarrassing as are those zangalewa clowns who appear at African national day celebrations dressed as colonial officials with cotton wool white whiskers and wearing khaki shorts and solar topees?

Thurman, the catalogue tells us, is “captivated by paradox, misperception and the inconsistences in human behaviour.” She’ll love this review, then. And, more to the point, she will presumably welcome the discussions her exhibition has triggered.

I wholly approve of the painstaking effort she put into making these heads and their meticulous finish, but I regret the triteness of their conception and their thudding lack of grace.

And that is a shame, because Thurman, who names Africa as a major influence on her work, is showing them at the One-Off in Rosslyn to the west of Nairobi (until April 3), which has a record of sensitive and exciting exhibitions and which rarely puts a foot wrong.

Trained in fashion and textiles design, Thurman produced collections under her own label before turning to magazine work as an art director and stylist. A regular exhibitor in the UK, this is her first international exhibition.

With her 3D heads filling the centre of the main gallery, it is to the walls that we look for relief.

There hang some 22 conte crayon drawings and oil monotypes of portrait heads on paper.

These are more spare and to my eye many times more effective than the sculptures. Some are enhanced by coloured washes that add texture and vitality.

To realise them, Thurman used a simple teaching technique; completing the subject without lifting crayon from paper. The result is a continuous line, which works even better when sinuous and expressive.

But here she has chosen to draw with the crayon at a similar weight throughout, opting for a descriptive surface pattern and leaving it to what little perspective there is to suggest depth.

The drawings and the moulded heads are clearly by the same hand, guided by the same eye, informed by the same brain; the surface takes precedence in both.

And the ears.