One of the first events organised by William Trevelyan was a mission in 1885. Canon Frewer described his experience of the mission:
'The flower girls of Westminster swarmed to the services, but were short of hats, so one girl would come into church for a turn, and then go out and lend her hat to a friend for a spell'.
Canon Frewer also described his personal experience of his stay:
‘St Matthew’s was said to be the poorest, dirtiest and wickedest parish in west London. I was billeted in Simpson’s [Revd H E Simpson] lodgings and I was devoured by insects. The squalor of the parish was generally terrible.’ 
Trevelyan also arranged for preaching in the streets as part of the Mission and introduced the Sisters of the Community of All Saints to the parish. In an obituary of Trevelyan, by an anonymous old friend of Trevelyan, and published in the parish magazine of 1929, he described the Sisters:
‘The Sisters were called in specially to visit the bad houses in the district but proving themselves to be such valuable aids in drawing all sorts and conditions to the Mission Services, it was realised that their help would be of greatest value, and should be made permanent if the work done in the Mission was not to be prospered and perfected. Thus the Community of All Saints became a recognised part of the parochial equipment, and still in 1929, Sisters of the Community are working in the Parish. ‘