After announcing a 15% rise in total sales to £880m for 2012/13 this week, Poundland has more than proved its ability to wrest customers away from the UK’s biggest supermarkets.

Once dismissed as one of the underdogs of British retail, the discounter has seen a meteoric rise in recent years. It’s now planning to expand its international business to several new European markets in 2014, having confirmed its Republic of Ireland start-up Dealz achieved a profitable first year of trading.

Meanwhile, Tesco saw like-for-like Q2 sales drop 4.7% in Thailand and 3.7% in South Korea, its two biggest markets outside the UK, and is cutting back on international expansion, or entering into joint-venture arrangements.

The message seems to be clear: the UK discounter model is safely translatable to foreign markets.

It’s on the home front, however, that Poundland is making real waves. Poundland boss Jim McCarthy, while teasing a stock-market flotation, insisted the company was on track to open 1,000 UK stores thanks to a rise in AB customers. You wouldn’t bet against him – especially as the likes of B&M Retail and 99p Stores are also growing rapidly.

With the big four (apart from Sainsbury’s, which also announced results this week) seeing topsy-turvy performance of late, it’s becoming possible to imagine a day when a discounter such as Aldi - hot off its own stellar results - could secure a double-digit market share.

The multiples are responding to this threat in varying ways. Asda president Andy Clarke told me recently he would look to “reduce the price gap with Aldi and Lidl on essential food items as much as possible”. Meanwhile Tesco MD Phillip Clarke’s approach towards the discounters feels like he is trying to swat an irritable fly; yesterday he declared 2014 the “year of the hypermarket”, and said he wanted to overhaul 60-75 superstores next year. And Morrisons and Sainsbury’s are marching on with their convenience plans – muscling in on high streets that may or may not contain a pound shop.

“I can’t get you out of my head,” as Kylie Minogue once sang; I’m certain that phrase sums up the big four’s feelings towards the discounters.