Boris Johnson’s partner Carrie Symonds has arrived at an environmental event known as the “birdwatchers’ Glastonbury”, where she is expected to speak publicly for the first time since moving into Downing Street.

Ms Symonds is set to give a short speech on her support for conservation during her appearance at Birdfair at Rutland Water Nature Reserve.

She will then join a question and answer session alongside guests including Chris Packham, presenter of BBC Springwatch.

She held an umbrella and wore green wellies, a floral dress and a red handbag as she arrived on a drizzly Friday afternoon.

Tim Appleton, founder of the birdwatching conference, said that the event has raised £40 million for global conservation projects in the 31 years that it has been running and described it as the “biggest ecotourism fair in the world”.

“We’re absolutely over the moon that Carrie is supporting us and we hope she will continue supporting us and conservation for many years to come,” he said.

He said he anticipated her speech would cover why she supports conservation, in particular ocean projects.

Public relations expert Ms Symonds, 31, resigned as director of communications for the Conservatives last year.

She is now a senior adviser at Oceana, a US-based environmental campaign group, working with its marketing operation in London.

A profile on the charity’s site describes her as being “passionate about protecting the oceans and marine life”.

More than 24,000 people attended Birdfair last year across the three days of the event.