Cassini House, St James’s, offers premium turnkey office space in one of London’s most distinguished districts
Nestled in the heart of St James’s, Cassini House presents a rare opportunity for businesses seeking a prestigious London address combined with exceptional specifications and amenities. Located on St James’s Street, this Grade A office building delivers a refined workplace experience in one of the capital’s most exclusive and historic neighbourhoods.
The 3rd floor has been comprehensively refurbished to deliver 6,887 sq ft of fully fitted workspace, ready for immediate occupation. The space includes 48 open plan desks, a range of meeting rooms (including 8-person, 6-person and multiple 4-person rooms), as well as breakout areas, agile working space and a dedicated reception/waiting area. Designed with flexibility in mind, the layout can be adapted to suit different occupier needs, making it an ideal turnkey solution for modern businesses, on very flexible lease terms from 12 months.
The building itself benefits from a remodelled reception, a brand-new communal roof terrace, end-of-trip facilities including showers and lockers, bike storage, and 24-hour security. With three passenger lifts and a goods lift, alongside high-quality air conditioning and raised floors, Cassini House combines contemporary functionality with premium finishes.
A micro-location defined by heritage and prestige
St James’s is one of London’s most historic and distinguished districts, long associated with royalty, aristocracy and private members’ clubs. Developed in the 17th and 18th centuries, the area has retained its reputation as a centre of influence, elegance and discretion, attracting global institutions and prestigious occupiers.
Today, Cassini House sits within this unique context, surrounded by heritage architecture, luxury retail and some of London’s most renowned institutions. From Jermyn Street’s world-famous tailoring to the iconic clubs and galleries nearby, the area offers a working environment that blends tradition with contemporary appeal.
What makes this location particularly special is its proximity to some of London’s most recognisable landmarks, including Green Park, Piccadilly Circus and St James’s Square—all within a short walk.
Exceptional connectivity and world-class amenities
Cassini House benefits from excellent connectivity, with Green Park station just a 3-minute walk away and Piccadilly Circus within 6 minutes. From here, occupiers have access to multiple Underground lines, providing seamless connections across London. Key transport hubs including Charing Cross, Victoria and King’s Cross St Pancras are all easily accessible, while Heathrow and Gatwick airports can be reached in approximately 45 minutes.
For businesses that value client experience and employee wellbeing, the surrounding area offers an exceptional range of amenities. Green Park and St James’s Park provide nearby green space—ideal for a lunchtime reset or informal meetings outdoors.
The local dining and hospitality offering is equally impressive. From iconic venues such as The Ritz and Franco’s to globally recognised restaurants like Gymkhana, The Wolseley, or Amelia’s personal favourite Maison Francois, St James’s provides an unrivalled setting for client entertainment.
Ideal for astute occupiers seeking flexibility
Cassini House is perfectly suited to financial, professional and corporate occupiers, as well as businesses seeking flexible lease terms in a prestigious West End presence. The combination of prime St James’s location, high-quality fit-out and immediate availability makes this an outstanding opportunity in a highly sought-after market.
The 3rd floor is available now, offering a fully fitted, flexible workspace solution in one of London’s most exclusive office destinations. For further information or to arrange a viewing, please get in touch with Amelia Royds, Catherine Lloyd or Ted Parr at RX London.