My roots are more Irish than British (or more accurately English), but there’s a limit to what one can do with cabbage and potatoes. Which was pretty much the British attitude to treating my Irish ancestors with murderous contempt as a bunch of cabbages and potatoes during the Famine. But that is all forgotten now, as the Poms have done so much more since to piss off the Irish. 
Anyway, a great dish can be made by taking some mashed potato and adding shredded cabbage, bacon (or cooked corned beef), pepper, mace, and frying the lot in bacon fat and or butter and you have a very nice Colcannon.
It’s better if you saute small cubes of parboiled but cooled and dry potato rather than using mashed potato, and then add the other ingredients. It gives you a meal of identifiably different tastes and textures rather than a somewhat mushy oversized rissole, and with nice crispy bits of spud in it.
But if you are going to use mashed potato just mash the boiled spuds because if you try to fry mashed spuds after milk has been added you’ll never get them to brown properly as there is too much moisture in them.
) doses of the standard fare or eggs, sausage, bacon, potatoes, etc. But also blood sausage is common and part of the traditional means of stretching any source of protein for people of lessor means, though now it’s apparently considered a delicacy eaten by many. It’s certainly not widely eaten in the US though I’m sure parts of Canada indulge in it and I’m sure it’s available at some of the ethnic stores here.