McDonald's has announced that it will be launching a brand new milkshake within days but British customers will have to act.

The Grimace Shake, which is already popular stateside, went viral when it was introduced to US restaurants last year.

The purple drink blends together a blueberry-flavoured syrup with the brand's iconic milkshake base.

The cool beverage is inspired by the chain's monster-like Grimace mascot which was introduced in the 1970s.

He was originally a villain who stole milkshakes from customers but was later rebranded into something more child-friendly.

How to get your hands on the McDonald's Grimace Shake as it lands in UK restaurants

The Grimace Shake will be available in most UK McDonald's restaurants starting Wednesday, August 28.

However, those in London may be able to try the shake before anybody else with select locations selling the item from today (Monday, August 26).

According to The Sun newspaper: "Box Park Shoreditch is selling the Grimace Shake from 12pm-6pm on Monday, August 26."

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Those looking to try The Grimace Shake will need to act quickly as it will only be available for one week, meaning customers will have to snag one before September 4.

The milkshake will set Brits back around £2.69 for a medium size, while a large version of the shake will be priced at around £2.99.

It should be noted that prices may vary depending on the location the product is being sold.