If the previous occupants had a compost heap and used their compost around the garden that is another possible source of potato plants. If you get freezes they will not survive.

@robert567 I'm in the middle of the UK. Not had the first frost yet I don't think? Maybe start afresh next year

Right, if you're in the UK, potatoes will not grow any more this year nor crop in the winter. Sometimes the odd spud survives the winter in the ground and sprouts again the following year. But it's not a dependable way to get potatoes. If you want to grow them you'll need to start again with next year, preferably with certified seed potatoes.

You can dig up the potato plants and see if there are any potatoes worth eating anytime.

OP says there are small potatoes. We’re likely to get a frost tonight, or at least very soon. The potatoes will not develop any further.

eta no frost, after all. It clouded over and rained instead.

I have had potatoes growing in the ground a little after top was dead, but it is better to harvest before or within a couple days of a frost.

OP describes the potatoes as ”tiny.” I doubt they’re worth harvesting and they won’t get any bigger.

Whether worth bothering to eat or not, if you want the potatoes out of the flower beds, you should remove them now before the plants wither.