It seems like the Trident is also related to Britannia, the personification of Britain - which is also related to triangles and triumphs...
Quote:
It was during the reign of Elizabeth I that "Britannia" came to be viewed as a personification of Britain.
...
One pageant performed on the streets of London in 1605 was described in Anthony Munday's Triumphs of Reunited Britannia:
On a mount triangular, as the island of Britain itself is described to be, we seat in the supreme place, under the shape of a fair and beautiful nymph, Britannia herself...
