Viewers to RTE's new series The Model Agent will see a surprising development on tomorrow night's programme when it emerges that one of the show's finalists has been wearing a wig. The secret of the hairpiece only came to light when the programme's finalists were flown to London for a modelling assignment. It was while undergoing a challenge there that programme-makers realised that one girl's locks were not as they seemed.

According to an RTE insider: "It turns out the girl suffers from alopecia and wears a wig. The show's producers, Erin O'Connor, Fiona Ellis and the five other finalists knew nothing about it but were extremely supportive of the girl when she broke the news."

Programme sources stress the discovery will not hinder the girl's chances of winning The Model Agent.

Neither should it. TV presenter Gail Porter has continued her career despite losing her hair to alopecia while Hollywood stars Sigourney Weaver, Demi Moore and Natalie Portman have all shaved their heads for a series of film roles.

On learning of the girl's condition, the programme makers decided to use the opportunity to examine alopecia, interviewing the finalist about her condition and how she has successfully overcome it.

"It was a bit of a shock to everybody but has been turned into something very positive. There are always these kinds of moments in reality shows – this is one of the more memorable ones but the matter was handled in a very sensitive manner," an RTE insider added. However the station declined to give an official comment.

With six girls left in the contest, tomorrow night's programme will see the remaining finalists whisked off for a fashion challenge in Topshop, a make-over at the London salon of celebrity hairdresser Daniel Galvin and their first casting session at Harpers Bazaar magazine.

A source said "Every young model wants to appear in Harpers Bazaar but can't get seen. Having Erin O'Connor involved really helped. Erin has such a great reputation it meant that all the fashion editors in London wanted to meet the girls she was looking after and for some of them it could be their break into the big time."

One girl will be voted off tomorrow night's show, leaving five to travel on with O'Connor to Paris and New York, where she will continue to share her tips on being a supermodel.

Erin (31) whose parents are both Irish, has revealed she has become firm friends with some of young Irish models since beginning work on the show. She said: "What distinguishes the Irish girls from other models is their humour – very witty, very down-to-earth."

With the overall winner of The Model Agent to appear on the cover of Image magazine, and be represented by top London model agency Independent, it's nice to know that model agent Fiona Ellis is being looked after too. Last week Ellis was signed up by top agent Noel Kelly, whose stable of Irish TV stars include Ryan Tubridy, Gerry Ryan and Lorraine Keane.