Wilde will now work two days a week as community affairs and events manager, spending the rest of her time building a client base for her own newly established company, Pink Carpet PR.
Wilde attributed her decision to step down to a ‘life change’. She will still handle events management, community support and train launches for the train firm.
First Great Western came under scrutiny earlier this year when it emerged that one in five of its trains is late.
Former Royal Mail head of external comms Richard Smith has taken over as interim head of comms. He was most recently a director at Bristol marcoms agency Proteus.