Martin Lewis has shared the hidden way in which people can gain access to shop at Costco stores in the UK, even if they don’t usually qualify to be a member.

The popular retailer, which has 29 stores across the UK, offers its members and their partners lower prices for buying in bulk, but it can be difficult to gain access sometimes.

Only certain professions can apply for in-store membership, which is priced from £26.40 per year, including business owners, government workers, bankers or police.

However, even if you don’t fall into one of the many categories stated, you could still start saving with Costco.

Money Saving Expert (MSE) founder Martin shared advice with shoppers, revealing there are some membership options that exist, but Costco doesn’t tend to advertise them.

The MSE website states: “AA, RAC and National Trust members are eligible to join at certain locations.”

The retailer does not advertise these membership options, but the financial gurus at MSE checked with UK Costco stores to see if the speculation was true.

While it doesn’t seem to extend to every Costco branch in the UK, they were informed that AA, RAC and National Trust members could qualify to shop at stores in Birmingham, Sheffield and Cardiff.

However, there’s a catch.

You can only shop at the location you joined at. Martin advised calling before making your first trip, just to double check the rules in place at your local Costco.

The experts at MSE have also shared some advice for those heading to Costco to do a big shop, as it can be tempting to quickly overspend thanks to the various offers and discounts.

Costco UK stores can be difficult to gain access to. (Getty)

The experts claim it can be sensible to make a shopping list and stick to it as you navigate your trip to Costco, branding it the ‘number one rule’.

Otherwise, the discounts and huge range of products could mean ‘you’ll pop in for bog roll and come out with a canoe, a 6ft teddy bear and a crate of 30 Danish pastries.’

They also advise being slightly sceptical of deals, adding: “Just because something graces Costco’s shelves, it doesn’t automatically make it a good deal. Always do your own research first and check if you can get it cheaper elsewhere.”

Compare unit prices as you go or download the Trolley.co.uk app to compare while out and about. Costco can often be cheaper for branded goods, but other supermarkets such as Aldi and Lidl might come out cheaper for own-brands.