She claimed he had 'deliberately misgendered' her on three occasions by saying 'all right geezer' to her when they passed in the street.
She said he also stared in between her legs and laughed, prompting her to alert PC Abi Chapman.
But PC Chapman told the appeal at Luton Crown Court that she did not recall Mr Mussington being there.
The 16-year-old, who was born female, claims he was effectively excluded from the school because staff refused to let him wear a boy's uniform.
The teenager is suing his former school under the 2010 Equality Act.
A fortnight later, Miss Gullon claimed Mr Mussington said 'all right geezer' to her again when he walked past her.
But she said the offender was aged 35 to 40 with short hair and a mark on his cheek, but he is older, bald and has no such mark.Erin Bisson, 40, from Jersey, launched a discrimination case after she was left 'humiliated' by Condor Ferries.- In 2013 PC Emma Chapman sued her force for allegedly making her 'out' herself to hundreds of officers.PC Chapman, who was born male and went through gender reassignment, claimed Essex Police control room staff had challenged her identity when she called in on the radio.Details of the British Medical Association's advice came in the wake of the case of Hayden Cross, 20, who is five months pregnant.Mr Cross, who was born a girl but is in the process of changing gender, has had hormone therapy and is legally male, but has not had sex-change surgery.- Last year a ferry company was forced to change its toilet door signs after staff told a transgender taxi driver to use the disabled loo.At the appeal hearing on Thursday, Miss Gullon, 47, gave evidence from behind a screen.