The Devon and South West Schools’ 800m champion clocked nine minutes and 43 seconds for the event to win by 12 seconds.
Blake was well ahead of the rest but the next four positions were decided by a sprint finish, with just four second separating second from fifth.
Ben Hall was runner-up in 9.55, with Plymouth University’s Oli Wright third in 9.56, Frankie Alred fourth in 9.57 and Erme Valley’s Nathan Brown fifth in 9.58.
Brown ran four seconds quicker than last month when he took second behind British youth triathlon champion Travis Bramley.
Tavistock’s Sarah Bull was first women home in 12.00, finishing 12 seconds ahead of Plymouth Harriers’ Jane Allison, who had edged her out on the opening race in October.
Plymouth Tri Club’s Nicola Noble was third women in 12.40.
View full results HERE