Bit of a late reply but there is a recipe for suet-less dumplings here. I've made them a few times and they were really good.

Atora Suet can do it.....

It also makes a nice crisp pastry.

As an alternative google a cobbler recipe for stew or savoury mince. It is a scone based dumpling that you cut out and layer around the edge of the stwen- a bit of cheese on them is always welcome

Hi, I know this is 5yrs after your original post, but did you ever find these elusive dumplings James Martin made? Me and my girlfriend saw them recently on T.V (saturday kitchen best bites or something) and the closest I've came to finding them is your post from 5 yrs ago! If you found the recipe or even the name of the cookbook they're from I'd be very grateful. Thanks in advance for any help