London Box Sash Windows Ltd, a family-run manufacturer and installer of bespoke timber sash windows and doors for period homes across London and the South East, has been named a finalist in The Customer Loyalty Award at The Lloyds British Business Excellence Awards 2026.
Operating in the premium home improvement and heritage property market, the company combines traditional joinery, conservation expertise and modern manufacturing to produce high-quality, energy-efficient windows that preserve the character of Victorian, Georgian and Edwardian houses. Its shortlisting recognises a service record the business says is built on doing what it promises: arriving on time, communicating clearly and resolving issues properly.
Craftsmanship meets continuous improvement
What sets the firm apart, according to the business, is an unusual blend of craftsmanship, technology and people-first leadership. It has invested heavily in machinery, training and its own bespoke CRM and manufacturing system, designed to give customers a more reliable experience from survey through to installation. Lean manufacturing, Kaizen-style improvement and defect logging are embedded in weekly meetings, helping the team raise quality, cut waste and solve problems quickly.
The company reports that it is the number one rated timber sash window company for London and the South East on Which? Trusted Traders, supported by genuine positive reviews.
People kept, profits reinvested
Growth has been steady and, the company reports, achieved without churn. From two people the business has grown into a 21-strong group spanning London Box Sash Windows and its sister glass business, Lead Designs, while maintaining zero staff turnover over the past five years. More than £4m has been reinvested in plant, machinery, systems and people, according to the business, and apprentices have progressed into management roles. Staff benefit from above-industry pay, profit share, half-day Fridays, regular catch-ups and an in-house gym, support the company links directly to the consistency of its customer service.
Sustainability is a growing focus too. Timber offcuts are turned into wildlife products through the firm’s Sawn To Be Wild initiative, trees are planted for products sold, and waste reduction is a standing priority, according to the business.
Recognition at Grosvenor House
The company’s roots run deep. Its website records that engineer John Ellis founded the business in 1980, with sons Jack and Patrick now running day-to-day operations from its Croydon workshop and the firm states it is FENSA registered, approved to self-certify that window and door installations comply with building regulations in England and Wales.
London Box Sash Windows says it stands out because it has modernised a traditional craft without losing its family values, long-term customer relationships or commitment to quality. Announced among the finalists in July 2026, it now competes for The Customer Loyalty Award, with winners across The Lloyds British Business Excellence Awards revealed at Grosvenor House, London, on 10 November 2026.
