Oxford University student Trigg leaped 15.41 metres to secure the title and add it to the BUCS crown he won earlier this season.
Former Ivybridge Community pupil Trigg was by far the most consistent jumper on the day, with all his leaps, apart from two no jumps, over 15 metres.
Blackheath’s Jonathan Ilori was second with 15.22 and Scunthorpe’s Jimi Tele third with 15.15.
However, the qualifying distance for the European Junior Championships is 16.30 metres.
Trigg’s Erme Valley team-mate Carie Robertson missed out on reaching the final of the under-20 women’s 400m hurdles final.
On Sunday, City of Plymouth athlete David King will be hoping to also had the England Under-23 Championship title to his BUCS crown in the 110m hurdles.