A senior member of the Royal College of General Practitioners was under investigation last night after advising medical students to act less “overtly gay” to ensure they passed exams.

The RCGP launched the inquiry after it emerged that Dr Una Coales had written a guide setting out ways in which minority candidates can “neutralise bias” from the college's examiners.

Dr Coales, a member of the college's council who came third in this year's ballot for presidency, suggested gay students speak in deeper voices and alter their body language to increase their chance of success in the RCGP's Clinical Skills Assessment.

In one passage of the guide, Dr Una Coales's MRCGP CSA Book, she writes: “One candidate was facing a third sitting and yet no one had told him that his mannerisms, gait and speech were too overtly gay, and that he was sitting an exam administered by a right-wing conservative Royal College.

“So I advised him to lower and deepen his high-pitched voice and neutralise his body movements. He went back to his surgery, practised his speech until his voice went hoarse and modified his body language. Not only did he pass his exam, but he informed me he noticed a huge difference in the way patients interacted with him.”

She also advises candidates such as Nigerian and Asian trainees to “focus on emphasising the lyrical Scottish or Welsh accent” if sitting exams in these regions. Female candidates should not wear a floral dress as “if you dress like a nurse they [patients] have difficulty believing they are seeing 'the doctor'…” Male students should “shave off” facial hair as it can project an “unclean, deceitful” image, she adds, in a chapter originally published in a medical magazine in 2009. Meanwhile, she advises overweight students to “project an image of Santa Claus. Put your hands on top of your protuberant abdomen, with your fingers interlocking but open.”

The RCGP's chief executive, Neil Hunt, last night referred her to the college's board of senior officers to investigate after being alerted to the book by The Independent. “The RCGP does not endorse the book, the author did not write it in her capacity as a member of the RCGP Council, and we reject the advice given,” he said. “The Clinical Skills Assessment is one component of a robust examination, approved by the General Medical Council, that all GPs must pass in order to enter into independent general practice. It reflects the diversity in general practice and within the college. I have referred the matter to the senior officer team of the college.”

Approached for comment last night, Dr Coales said: “I'm not for a minute suggesting the college is racist or homophobic. These are merely tips to neutralise subjective bias, if any, in 10-minute assessments involving a total of 26 random actors and examiners who have never met the candidate.” Dr Coales has previous stated of her advice: “All of my suggestions are simply about getting you through the CSA. They're about changing your image to get you through this one assessment. They're not about changing who you are.”