Deluxe delight

It's not often that you get to stay the night in your old bank, but this is precisely what happened when I spent the weekend at luxury hotel Sofitel St James, just off London's Piccadilly. Formerly the headquarters for Cox & Kings Bank and more recently Lloyds Bank, the hotel exudes a refined grandeur, outside and in. Centrally situated in Waterloo Place on the corner of Pall Mall, the Grade II-listed building has an imperious air about it and sits perfectly alongside the Neo-Classical architecture of nearby Regent Street.

Designed by E Keynes Purchase and completed in 1923, the 125,000ft² building is owned by The Crown Estate. The architect behind Sofitel St James is award-winning London-based company RHWL, which built its reputation redeveloping and refurbishing visually sensitive and historic locations.

Inside, the hotel's banking history is tastefully celebrated, but not overblown; from the stunning 3m-high engraved glass wall at the entrance, which details the building's original use, to the paintings and meticulously restored bank memorabilia taken from the boardroom of Cox & Kings. The decor in the impressive double-height lobby includes some specially commissioned pieces by French and English contemporary artists, such as Elisabeth Stenne and Fitzia.

Renowned French interior designer Pierre-Yves Rochon has successfully created a balance between the building's original elements and a more modernist approach. The smooth lines of the semi-circular mezzanine floor overlooking the lobby and where a pianist plays in the evening being a case in point.

The sheer volume of the entrance area and reception is tempered by some more intimate spaces leading off it. With its dark wood bar, black leather armchairs and plaid-covered walls, the cosy St James Bar has the air of a gentleman's members' club about it. After a day of serious sales' shopping on Regent Street, we came back here for a mean gin martini, deftly prepared by charming French staff dressed neatly in black.

Business as usual

The conference and meeting rooms at the hotel have a glamorous feel to them with their array of decorative glass, crystal and porcelain chandeliers. The presidential suite, newly renovated by the interior design company Sparc Studio has its own art installation and is regularly used by the big film studios for press junkets.

A rose is a rose

Offsetting the masculinity of the bar is the Rose Lounge, an unabashedly feminine space and home to the hotel's library. This veritable homage to the flower in sight, with its cream and pink decor, and smell, with its profusion of fresh flower displays, is a popular area for afternoon tea accompanied by the sound of a harp.

Brasserie Roux

Inspired by celebrated French chef Albert Roux, the elegant restaurant occupies the former banking hall at the corner of the building and boasts three 15ft-high arched windows. Particularly impressive was the Roux express lunch, which promised a four-course lunch within 45 minutes or your money back. It certainly delivered. We ate beautifully fresh French brasserie-style food in the company of a well-heeled crowd, and all for just under £20.

And so to bed…

The hotel is spread over five floors and has 186 rooms ranging from classic and luxury, to junior and prestige suites. Ours was a spacious luxury room, elegantly decorated in muted brown, green and grey tones, offset with chrome fittings and thick flannel fabrics. The Art Deco-style touches were an unmistakable nod to the building's 1923 inception. Everything about the room spoke of understated luxury, from the thick pile wool carpet and Zoffany-style wallpaper to the Hermès toiletries in the monochrome bathroom.

Every room in the hotel features the 'MyBed' concept – a mixture of the highest-quality Epeda foam-base mattresses and generous feather-down mattress toppers (all of which can be purchased for those who want to recreate the concept at home). The result was so cosy, it was like being cocooned in a cloud.

There were magnificent views from the room over Pall Mall and Waterloo Place and the tranquillity of the hotel belied its proximity to the hurly burly of Piccadilly Circus, a mere five minutes walk away.

The SoFit gym

Looking to recharge my batteries after a morning of sightseeing, I sought out the gym, newly refurbished and offering some of the most advanced, state-of-the-art gym equipment around. Walls of fresh greenery set behind glass gave the space a clean and Zen-like feel. And nothing could be more Zen than the cutting-edge Sha Chair – 25 minutes of sounds and sensations on your body while lounging on a specially moulded chair. Guests looking for a tougher regime could do well to try out the new 'boot camp' package at the hotel, where personal trainers put clients through their paces in nearby St James's Park.

The spa

Just off the main lobby, and accessed through a beautifully illuminated walkway, the Sofitel St James Spa is like stepping into a French garden, complete with streams of running water and elegant topiary. Housed in a building adjacent to the hotel (formerly the Bank of Nigeria), the building has been renovated to incorporate the spa, while simultaneously protecting its traditional features.

The solid oak staircase, rose-coloured marble walls and Corinthian-style columns still remain in all their glory. In the treatment room, the thick wooden doors of the former bank, and the intricate plaster ceiling mouldings were a dazzling contrast with the moody low lighting and modern Wenge wood wall panels.

Many spas these days tend to look alike and the tireless reworking of south-east-Asian-inspired decor is a little hackneyed. Not so here. Beyond the spa reception and in the vaulted space of the old banking hall, stands a stunning oak pavilion with exquisite Charles Rennie Mackintosh-style ironwork panels. This eye-catching structure contains a long marble table complete with mother-of-pearl inlays, where you can sit and have tea or browse the beauty ranges on display. Natural light flowed in abundance from the two large frosted windows – unusual for a London spa.

My very own 'spa butler' gave me a tour to help me choose my treatment and each room was more tempting than the next. Would I sample the private Turkish steam bath (hamam) with its centrally heated marble treatment bed? The Kohler Soak infinity bath with chromatherapy? Or the Astorina bath with hydrotherapy jet? In the end, I plumped for their highly popular signature beauty treatment – the Zenith Treatment with Baccarat. An hour of facial massage using luxurious products including essential oils and, to my delight, warm stones. Afterwards, I was invited by my personal butler to take tea (complete with a crisp Ladurée macaroon) in the So Zen relaxation room. From the soft white blankets to snuggle in post-treatment, to the room temperature tailored to your preference, every detail in the spa has been carefully considered.

French fancy

The French-owned hotel prides itself on its art de vivre. Its predominantly Gallic staff dart efficiently around the hotel warmly greeting guests and accommodating people in the way that the French in this industry excel. I am told Nicholas Sarkozy has stayed here, as well as members of the French and German Governments and I'm not surprised. This hotel, with all its quiet elegance and sense of history, has attention to detail in spades, but without the pomp that often comes with this level of luxury.