On 20 July, 12:28, Andy wrote:
But the wording isn't beyond 'London Terminals' but beyond London.
You'd be hard pushed to argue that Kentish Town isn't in London.

Yes. And as such it falls into the same pricing regime as London-
Ashford:

ANYTIME DAY SINGLE NOT VALID ON HS1 22.60 GBP
ANYTIME DAY SINGLE ANY PERMITTED 27.00 GBP
FIRST ANYTIME DAY SINGLE ANY PERMITTED 33.90 GBP

OFF-PEAK DAY RETURN NOT VALID ON HS1 23.10 GBP
OFF-PEAK RETURN NOT VALID ON HS1 28.60 GBP
ANYTIME DAY RETURN NOT VALID ON HS1 40.90 GBP
ANYTIME DAY RETURN ANY PERMITTED 49.00 GBP
FIRST ANYTIME DAY RETURN ANY PERMITTED 67.80 GBP

(from thetrainline.com)

So the prices at the start of this thread are incorrect or out of
date, and the loophole does not exist*.

(* it may do for another station in London, but I doubt it)

U