I reported finding one of these last year at Northiam. Here is another likely specimen, found at Staplehurst, so rather pushing the RX area boundary a bit, but there is potential to find more of these hybrids I suspect.
In this animal there is a tail filament (a short narrow thread-like extension at the end of the tail), as in the palmate newt, and the rest of the tail looks more like a palmate newt in colour pattern. The crest is low and the body rather square-shaped, again a palmate feature. However the spotted throat is typical smooth newt, as is the spotted belly pattern. The hind feet have neither the prominent black webs of the palmate newt, or the toe fringes of the smooth newt, but do have a poorly developed set of translucent webs.
As with the animal I found last year it’s similarity to either parent species varies during the day, looking more like a palmate newt in colour at night, and more like a smooth newt during the day.
I do wonder how many of our ponds have these hybrid newts quietly going about their business. The females would be very hard to distinguish.