Modelstories website points out, that the
red missile may appear strange but a mock-up was
employed in one of the Tridents in reality
(confirmed by
this picture). I found more pictures from the
Trident with a missile in the book : X-Planes of Europe:
Secret Research Aircraft from the Golden Age 1947-1974
by Tony Buttler, Hikoki, 2012 ,as well in the
Aeronef Forum and in 1000
1000Aircratfphotos.com.
Long boxend above, Short boxend right
Specification and history
of all Solido kits included in box. It seems to be
included originally as I found this Documents
as well in my other copy of the Trident.
Click for larger resolution.