A transgender police officer who sued her force after she allegedly had to “out” herself over a police radio system has lost her case at an employment tribunal.

The tribunal said that Police Constable Emma Chapman was “unreasonably prone to take offence” and her reaction to requests for confirmation of identity had been extreme.

The judgment was delivered last month but has only just been made public.

PC Chapman brought the claim against Essex Police after she said she was forced to confirm that she was transgender over a police radio.

PC Chapman complained after several incidents where her gender was questioned by control room operators who wanted to verify her identity as a woman because they said her voice sounded male.

The 44-year-old alleged that on the first occasion, in October 2012, the operator did not believe who she was, saying she had a “male voice”.

Two further alleged incidents occurred in June 2013 when the officer was again challenged by control room staff who questioned her identity.

In October, Essex Police said it “disagreed” with PC Chapman’s assertions.

A spokesman acknowledged that conversations between PC Chapman and the control room had taken place but said the force disputed the “precise wording and tone” said to have been used.

PC Chapman had previously turned down an out-of-court settlement.