A number of public spaces at the luxury London property had already welcomed back guests in December, with the rest of hotel’s areas reopening on April 15.

Mandarin Oriental said it had used the opportunity for repairs to give the hotel its “most extensive restoration in its 117-year history”.

New guest rooms and suites, including two newly created penthouse suites, are set to be unveiled as part of the reopening.

Designer Joyce Wang has overseen the redesign of all guest rooms and suites, along with the creation of the penthouses.

Each of the hotel’s 40 suites range in size from the smallest, at 47 square metres to the largest, at 444 square metres, are located within the turrets of the hotel which comprise the new three-bedroom Mandarin Oriental Penthouse with private terraces.

Comprising two penthouse suites, the Mandarin Penthouse and the Oriental Penthouse can be interconnected “to create one of London’s largest suites”, with three bedrooms, three bathrooms, a private dining room, two kitchens, and views of Hyde Park and the London skyline.

New York designer Adam D Tihany has overseen the redesign of the hotel’s spa, which now features 13 individual treatments rooms, an Oriental Suite with two massage beds and a Rasul water temple as well as a Bastien Gonzalez Pedi:Mani:Cure Studio – claimed to be the first of its kind in the UK.

Tihany has also overseen a “light refurbishment” of Dinner by Heston Blumenthal, Bar Boulud, London and Mandarin Bar.

The Rosebery, known as the Bennett Tearoom in the 1920s, will offer a special afternoon tea from the period, while Mandarin Bar has created a series of special cocktails named after celebrated guests and iconic events to have taken place within the hotel.

The hotel’s Ballroom and Loggia have also been restored to include 24-carat gilding of many original features.

There are also two new meeting spaces, Asquith and Balfour, for private meetings and social gatherings.

Amanda Hyndman, general manager and area vice-president of operations, said: “Mandarin Oriental is enormously proud of the heritage of this historic hotel.

"The scope and intricate detail of this momentous renovation is designed to ensure this iconic London establishment is recognised as one of the finest hotels in the world.

“We look forward to welcoming our guests with kind and intuitive service that is truly British but reflective of our Oriental heritage.”

To mark the reopening, Mandarin Oriental has created a Be the First to Stay package available from April 15 to June 30.