Those planning to jet off on holiday anytime soon have been advised to pop a couple of tennis balls in their hand luggage for a very smart reason. The advice was given by British Airways, which noted essential items that would be in every "clever" traveller's carry-on.

It noted that hand luggage is for more than just the flight, and whether you're travelling on a quick journey or heading off on a well-deserved long break, there are some items that are absolute musts when packing your on-flight bag.

While tennis balls might be unexpected, they certainly do come in handy for one crucial thing - improving your blood circulation.

Long flights typically increase the risk of poor blood circulation, which can lead to swollen legs and, in worst-case scenarios, potential blood clots. While many people use compression socks, drink plenty of water to stay hydrated, or walk up and down the aisle, adding another preventive measure is always a bonus, and that's where the tennis balls come in.

British Airways explained: "While we're not suggesting you do the full Federer or Raducanu on your trip, toss a pair of tennis balls into your carry-on as they're an ace massage tool.

"Gently roll them beneath your feet during a flight to improve circulation and as a kindness to achy soles and calves."

The balls can also help with any soreness you get from travelling, making them useful not only on the plane but also when you get to your accommodation.

The airline added: "At the hotel, lay a towel on the floor or stand against the wall, place the balls behind your shoulder blades and move them up and down or sideways to help work through any stiffness or knots. Plus, of course, if you hear 'Anyone for tennis?', you're all set."

So, the next time you plan to catch a flight, as well as all your holiday goods, make sure you have one or two tennis balls coming along with you.