Donald Trump and roast potatoes have more in common than similar powers of reasoning. Just as the vainglorious presidential hopeful finds himself splashed across the front of the tabloids, an equally troubling potato-related danger lurks within the papers.

Forget the prospect of Trump pulling the strings or pushing the buttons as he escalates World War Three. That’s all in the future. As of this week, all-out supermarket war is raging right here in the UK. The big Christmas Shop is approaching and full colour display ads have flooded the popular press, touting sprouts, carrots, parsnips and potatoes at cheap-as-chips prices. It sounds great, but there is a big problem. Like Trump, I’ve no wish to be a scaremonger. But everyone’s Christmas Dinner is in great peril.

We all love Christmas Dinner. Everyone is happy. Arguments are unheard of. It’s the one time of year anyone roasts a turkey. Even sprout apologists are appeased with good grace. And our plates are packed with plenty of other good-for-you vegetables. So surely Tesco offering 3.5kg of veg for £1.56 is a great thing for our wallets, bodies and our festive feast?

Almost. The problem is that a bad roast potato can torpedo any meal. Even a magnificent Christmas Dinner. And the supermarkets aren’t offering up the good roasters this Christmas at crazy prices. Even Trump could tell you that Maris Pipers are required to make great roast potatoes. In emergencies, a King Edward will do. What you avoid like mustard gas is the White Potato. No amount of pricey goose fat could properly roast a White. But that’s what Tesco is knocking out for 39p. And so is Asda.

Thankfully, Sainsbury’s and Morrisons are keeping their powder dry, for now. But the German discounters have advanced. Lidl has undercut Tesco by offering its spuds for 29p, but they are small potatoes described as ‘British Mini Roasts’. They look like new potatoes. At Christmas, I’d rather roast a White. Get back to the School of Christmas, Lidl.

The only beacon of light comes from Aldi, which is offering a 2kg pack of Maris Pipers for a ridiculous 29p (82% less than the price of a Piper in Tesco). And it’s bumped up the sizes of the other packs of veg, so you get 4.4kg of real deal spuds, plus carrots, parsnips and sprouts for £1.36. Staggering prices and proper potatoes, but Aldi only has a 5.6% share of the market. That’s not enough to keep us all safe from harm.

Clearly, this Trump-potato situation is a potentially grave one, both for our plates and for our planet. As Christmas approaches, we can only hope everyone thinks carefully and makes the right decision when the time comes. Because we are all at risk.