They are if they have red circles round them like the one in your first picture. The rectangular ones that don't have any red on them that you sometimes see on tight slip roads are not binding AFAIK.
From counting the cones, the camera looks to be about 150 feet beyond the red tarmac section and that's about 100 feet beyond the speed camera and 30 sign.
Braking from 50mph to 30mph should take about 2s and roughly 140 feet if my Google skills can be trusted.
Was the preceeding DC section 50mph or 70?
It was in a coned area where workmen /could/ have been. I think if you contest and lose, 3 points and £60 could look like a bargain.