Having had a quick look at this - either the Spex price or the Unibet price is wrong.. I'd go with Uni being wrong.
Looking at the maths if we assume GS matches will average 38 booking points and KOs 42, as a rough estimate I'd stick England in for 44% of books in their matches, using their percentage chance of featuring in each phase (from my model) I'd have England in for 92 booking points, that doesn't take into account any ET booking points, Spex midpoint is 103, and given that the market favours England more than my model I'm happy that the Spex price is about right - certainly in the right ball park.
Even though England are below average in terms of card gatherers in competitive matches v Top 100 in the last couple of years, taking into account teams will play a disproportionate number of matches I think it's worth chancing them at 25/1 for small stakes