The 25-year-old Londoner has not formally signed a contract with his new team, the Houston Rockets, but Britain have still had to pay a high premium to cover him to compete in this event, the first time they have qualified for the final stages since 1981.

Chris Finch, Britain's coach, said: "All our players are insured but Pops' situation was different because it needed a bespoke policy.

"You have to cover the gaps in insurance so his earning potential is not exposed."

Mensah-Bonsu has missed Britain's preparations for the Championships because he has been negotiating his contact with the Rockets and his return is a boost to a squad missing other NBA stars Luol Deng and Ben Gordon.

Finch said: "We're really excited to finally have Pops with us.
 
"Adding him is a boost; it keeps on strengthening the front line.

"The challenge now is to make sure we get him in as quickly as possible and hope he is in some sort of shape."

Ron Wuotila, the head of operations at British Basketball, said: "Thanks to the help from the Rockets and Pops we were able to put a policy in place in short order.

"This is a complicated process and was only possible with the help from many key people."

A similar deal last year for Deng, who is the Chicago Bulls highest-earning player, cost British Basketball $500,000 (£272,000).

Finch cut Justin Robinson and Jermaine Forbes from the final squad of 12 as Kieron Achara and Flinder Boyd also returned.

The team have been riddled with injuries, illnesses and player availability but with the first game in two days Finch has been able to train with a fully fit squad for the first time this summer, which made his decision to cut Robinson and Forbes even harder.

A fully fit Achara and Boyd will travel to Poland, alongside Mensah-Bonsu and Malaga pair Rob Archibald and Joel Freeland (pictured), while former British under-20 players Dan Clark will have the chance to make his senior debut in a competitive game when the team makes their debut in the tournament against Slovenia in Warsaw on Monday.

Finch said: "It's an interesting roster, we have a lot of depth up front in the big guys and that will be the strength we need to play to.

"But I also want to acknowledge the guys who didn't make the roster.

"Justin did a great job playing at this level and I'm sure he learnt a lot.

"This was probably the highest level he has played at in his life.

"He is definitely one for the future as he gives us some things we just don't have at the moment.

"I'm looking forward him making a big step between now and next summer.

"It was the first chance to see what Jermaine could do.

"He was extremely solid and I will be interested to see what happens with him over the next year.

"It was a difficult decision to leave him off but we went for youth in there instead, even though it's a little unbalanced.

"For the first time yesterday we had a chance to have our full squad train together.

"Everyone is in the right frame of mind to compete.

"Over the last couple of days there has been a good spirit in the team and I think everyone is looking forward to arriving in Poland.

"The key to competing internationally is understanding that you can't control your environment.

"When it comes to the national team you can't control certain aspects so you have to make the best of it and stay flexible.

"This year was a good example of that and we have had to demonstrate how we've had to be creative, but I'm confident we have it right."