"That has given out grants to half a dozen heritage projects in the city centre since then.
"The 30th Art Deco Festival was another massive highlight of my time here. We took steps to make it even bigger and even more of a community event and it went off without a hitch."
Gorst, who will finish up officially on August 31, added that working with the trust's dedicated volunteers was also a big highlight.
Trust chairman Neil Barber said the trust would be sad to lose Gorst but pointed out he has set the trust up well for "the next phase".
"He's given us 18 months of good service with quite a different style of leadership than his predecessor and he's set us up for the next phase of the organisation.
"His lasting legacy will be the establishment of the Robert MacGregor Heritage Fund and that will be something he is proud of and the organisation is proud of."
The trust hoped to have a replacement in place by mid-September, in good time for the next Art Deco Festival.
"We are quite a lean organisation, so you have to be able to work magic with limited resources but that person will be out there."