I can't read it as it's behind a paywall.
A Sunday roast is not unhealthy if you keep your portions sensible - good-sized meat portion for protein, lots of your veg of choice, but don't go mad with the roast potatoes. If you're having Yorkshire pudding, have a small piece if it's from a tray or a mini-sized one if using frozen. You don't need it to swim in gravy, either, just pour a bit on where it matters. You could also have boiled or mashed potatoes rather than roast if you want something lower in fat.
Or, you could take the view that if you eat healthily the rest of the week and you're not trying to address any health or weight issues through diet, have whatever you like for your Sunday roast! It's not a crime to have occasional meals that aren't the healthiest, as long as you are eating sensibly for the majority of the time and you yourself are healthy.