Britain’s two biggest discounters are one regulatory decision away from a very different growth plan. The Competition and Markets Authority is expected to publish a provisional ruling this month on whether Aldi and Lidl should be classed as Large Grocery Retailers under the Groceries Market Investigation (Controlled Land) Order 2010, a designation that would strip away a property advantage the pair have leaned on for years.
As things stand today, Aldi and Lidl sit outside those rules. That gap is exactly what rivals want closed, and the regulator’s verdict, with a final decision pencilled in for September, could decide how fast the discounters keep opening new stores across the UK.
What the CMA is actually deciding
The question in front of the regulator is narrow, but the consequences are wide. The 2010 order bans large grocers from using restrictive covenants, the property clauses that stop a competitor from opening on nearby land. In practice a covenant can sit on a plot for years, quietly keeping a rival off a site long after the original store first opened.
Seven of the biggest chains are already bound by it: Tesco, Sainsbury’s, Asda, Morrisons, Waitrose, Marks and Spencer and Co-op. Aldi and Lidl are not, because they have long been treated as limited assortment discounters, a category that kept them off the list when the rules were first drawn up.
The CMA is now assessing whether the two German owned chains have grown large enough to belong on that list. If it says yes, they lose the right to lock rivals out of sites near their own stores.
The loophole that helped build the discount boom
The exemption handed Aldi and Lidl a quiet edge during the exact years they were expanding hardest. While the majors were barred from restrictive land deals, the discounters could still use them, letting each one protect its patch as it pushed into new towns.
Rivals say that edge is no longer justified. Morrisons, Sainsbury’s and Iceland are among the loudest voices pushing the CMA to act, arguing the rules were written for a market that simply does not exist anymore.
The numbers behind the row
The scale of the shift is the heart of the complaint. A handful of figures set the scene:
- Aldi and Lidl’s combined grocery market share has climbed from under 3% when the regime was created to roughly 20% today.
- Aldi is now Britain’s fourth largest supermarket by market share.
- Lidl already runs more than 1,000 UK stores and has published a wish list of around 100 potential new sites.
- Six parties filed formal responses to the CMA’s consultation: Aldi, Iceland, Morrisons, Sainsbury’s, the Association of Convenience Stores and individual respondents.
Put together, those numbers explain why the majors feel the playing field tilted while they were watching. A rule that made sense when two challengers held a sliver of the market looks very different once those challengers control a fifth of it.
What a designation would change on the ground
A yes from the CMA would not shut a single existing store, but it would reshape how the discounters grow from here. They would lose the ability to write exclusivity clauses into new land deals, which makes it easier for rivals to open close by.
The timing matters because space is already tight. Industry analysts have described UK retail parks as effectively full after years of aggressive discounter expansion, so every remaining prime site is fought over. Take away the property shield, and Aldi and Lidl could slow at the very moment good locations are hardest to find.
Why this lands in a jittery year for the high street
The ruling arrives while the wider UK high street is having a rough 2026. Well known names have gone into administration or announced deep store cuts, and footfall on many town centres remains soft, so competition for the sites that still pull shoppers has rarely been fiercer.
That backdrop raises the stakes for both sides. For the majors, curbing the discounters is partly about defending market share they have been losing for a decade. For Aldi and Lidl, keeping the freedom to secure sites is central to a rollout plan they have promised will continue for years. Both chains have built their pitch to shoppers on always having a nearby store, and anything that slows new openings chips away at that promise.
What happens next
The CMA has set out a clear runway. Its invitation to comment ran from 12 March to 13 April 2026, and it published the responses on 5 May. The provisional decision is due this month, with the final ruling expected in September.
For shoppers, the immediate effect is nothing. Prices on the shelf will not move because of a land order. Over the longer term, though, the decision helps set how many discount stores open, and where, which is the ground where Britain’s grocery price war is really being fought.