Tridgell has a broad remit covering fundraising, marcoms and lobbying.
'The trust is one of the leading disability charities in the UK and we want that profile raised even further,' she said. 'We'll be focusing on national coverage of our work and regional exposure around our 25 UK centres.
'Another big challenge is to increase corporate and legacy donors,' she added.
The public affairs side of the role will involve getting close to ministers and explaining what the charity does, rather than campaigning on specific issues, Tridgell explained.
Speaking about her move from a marketing research discipline, she said: 'It might seem strange, but I spent five years as chief executive of the National Advertising Benevolent Society before joining Postar.'
The charity offers care, rehabilitation and support for people with profound physical disabilities, autism, brain injury and learning
difficulties via purpose-built accommodation and community-based housing.
Tridgell reports to chief executive Colin Hedley.