AREA: 27,950 SQ FT



Leslie Clark have been appointed to provide cost consultancy services on the refurbishment and two-storey roof-top extension of this existing headquarters office building of Howard De Walden Estates on 23 Queen Anne Street, in the heart of Marylebone.

The works will comprise the complete stripping out of the existing building back to frame and external walls, and alteration work to remove the upper roof and floors, and all of the external doors and windows.  The building will be extended with two new floors atop plus extensions to the rear, to provide additional office space and outdoor facilities with terraces on the 3rd and 4th floors, including a green roof and pavilion.

The building will be transformed and will provide a grade A quality product that will again be the Estates headquarters building, in line with Howard de Walden’s sustainability and net zero policies for all future developments. PVs and green roofs will be provided to the upper floors, together with sustainable floor, wall and ceiling finishes and new services installations.

The strip-out was completed as part of the main works under the appointment of the main contractor which was felt the right way to approach the project bearing in mind the extent of the strip-out and structural alteration works to be undertaken prior to rebuilding the offices.

The office floors of the building will be completed to a Cat A/B specification on the basis the tenant is the owner of the building. The specification will include raised access flooring with timber finish on top, plasterboard raft ceilings with bulkheads for the new building services and lifts befitting a Grade A headquarters office building. This Cat A/B specification will include all cellular offices, kitchen and dining facilities, end-of-journey experience and even a small gym/studio for staff.

  • Central London location and Westminster building requirements – the location of the project being in the heart of Marylebone and surrounded by adjoining medical buildings, required careful consideration of access and egress, traffic management, parking bay restrictions and importantly delivery of materials and equipment.
  • Craneage via luffing jib crane with oversailing restrictions. Craneage logistics – a crane was used during the construction of the two new upper floors.
  • Minimisation of disturbance to adjacent properties, limitation on working hours and noise reduction – part of the project mandate was to keep to an absolute minimum any disturbance to neighbours and adjoining buildings; adjoining properties were kept abreast of noisy works, weekly schedules, disruptive operations by way of regular Contractor newsletters
  • Structural works in the creation and addition of two floors at levels 4 and 5

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Leslie Clark specialises in the retail, office/commercial, leisure/hospitality, and residential sectors but has extensive experience of many other project types throughout the UK. Today we are at the forefront of sustainability alongside many of our clients.