Froome won the Tour for the fourth time earlier this year but he had never managed to follow up in the Vuelta.

But that all changed this time, the Brit having tinkered with his schedule somewhat in an attempt to try and remain in top form for the gruelling test the Vuelta provided.

The plan worked to perfection as Froome crossed the finishing line on Sunday with an advantage of two minutes, 15 seconds over Vincenzo Nibali.

Froome told Sky Sports News on Sunday night: "It's quite overwhelming.

"You start out at the beginning of the year and set the goal of trying to win the Tour de France and the Vuelta a Espana.

"It's such a massive challenge and it seemed quite daunting at the time. To be here in Madrid now and to have pulled it off is such an incredible feeling.

"It is not something I could ever have done on my own, so it is thanks to an amazing team around me and an amazing support structure as well."

Froome tweeted a picture of himself enjoying a pizza after the race and he added: "It has certainly been a long time since I have had a pizza.

"That was one of the little treats that get you to the finishing line!"

Cycling greats Jacques Anquetil and Bernard Hinault are the two men to have previously done the Tour-Vuelta double but the schedule has been altered since their day, making the feat even more difficult to accomplish.

Froome has won the Tour de France and the Vuelta this year

Froome explained: "It is a huge undertaking, especially since the Vuelta a Espana has been moved to after the Tour de France.

"This is the first time anyone has ever done it in history [since the change] and it is because the Tour de France takes so much out of you.

"Winning that and then getting back into training again and to get that focus again for another three-week grand tour is just such a big challenge.

"I am driven so much by the sporting challenge and the physical fight of it and it is such an amazing feeling and sense of achievement."

The Vuelta organisers devised a relentless schedule this year and Froome said he was not able to consider himself assured of victory until he had survived Saturday's epic stage.

"[That was] Probably the most gruelling climb of this year's addition," said Froome.

"It was a brutal stage with really quite horrific weather conditions as well and dangerous descents so, right up until the last stage, last night, it was not over.

"Today's stage was a bit of a celebration and it was amazing to cross the finish line tonight and know we can relax and celebrate this evening."

Froome took the lead on stage three of the Vuelta and did not look back

However, there is not much time for Froome to rest up, and he added: "Next weekend I have got the world championships in Norway.

"I will line up for the time trial with the rest of the lads. After that, I will probably need to take a bit of a break!

"I just want to say a massive thank you to all the support from back home, it has been absolutely incredible."