Mash is ok, but I don't like smooth silky mash which is just like the "smash" bought in packets and mixed with water. My favourite mash has "lumps in it" like the porridge that the Irishman said he enjoyed when he was stuck in Steptoe and Son's hovel after breaking out from the "scrubs" with his younger cellmate.
We would always have roasts potatoes with a roast. I'm actually making a fish pie now which son likes. Just waiting for pots to finish boiling. Everything else is done.
Roast potatoes are the first and most important element of a roast dinner for me, next come the roast parsnips, then the roast squash, some sprouts or other green veg, yorkshire pudding and gravy. If I could be bothered, I would have mash too and cauliflower cheese, but not instead of anything.
Sunday dinner here is
Roast beef or chicken ( don't like Pork and I find lamb a bit greasy )
Carrots
Broccoli or green beans
Turnip
Creamy mustard mash
Two large crispy roasties
And a golden brown Yorkshire pudding
With tonnes of meaty gravy
Never ever mash with roast lunch. It has to be roasties in winter and simply boiled new spuds in summer, always done with fresh potatoes, none of that Aunt Bessie's rubbish.