a family run business set in the heart of Buckinghamshire

About us

A wealth of over 25 years’ experience in the industry, we operate as an independent supplier to offer impartial advice and guidance on the best equipment and leading technology, creating the perfect building environment to suit your needs.

Mechanical services with a difference

How we can help

As a major competitor in the industry, the majority of our work is undertaken through repeat business and reputation. We have delivered numerous successful projects across the commercial, retail, industrial and residential markets, offering an end-to-end personalised and tailored service for all your Heating, Ventilation, and Air Conditioning requirements.

We opt for a simple and straight forward approach when doing business, always keeping our customers informed so you know what will be delivered, the time frames involved, and costs incurred through clear project management and planning exercises.

With a strong corporate and social responsibility embedded into our company ethics, we take a green approach and outlook on everything we deliver, which also gives you the peace of mind that you are proactively supporting the wellbeing of your employees, customers and the environment we live in.

Our credibility in the market and many successful projects delivered, gives GMS the highest confidence in the quality of our services which we utilise in all the customer projects we engage in.

Get in touch

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Our accreditations

Our credibility in the market and many successful projects delivered, gives GMS the highest confidence in the quality of our services which we utilise in all the customer projects we engage in.

Daikin Certified Installer Scheme

The Daikin Certified Installer programme is designed to promote and maintain the highest standards of practice and performance, providing enhanced warranties along with the extra credibility that comes from working with a market leader. As an established Daikin installer, our focus is on quality products, installation, and service – backed by high standards of training and accreditation.

Mitsubishi Electric Accredited Installer

Designed to raise industry standards, Mitsubishi Electric's Partner Programme assures end users of a consistently high level of installation and after sales service that supports our systems. Our Partner Programme is inclusive and open to all qualifying companies installing air conditioning and heating.

Safe Contractor

Safe Contractor accreditation has been achieved following an assessment of the contractor’s health & safety documentation, and compared against the Safe Contractor Charter Standards, which set out the health & safety standards required to achieve this accreditation. Safe Contractor also supports our business by helping us demonstrate commitment to sustainable and ethical practices.

F Gas

The F-Gas Register is appointed by the secretary of state for the environment, food & rural affairs (DEFRA) to operate an F-Gas Certification body under the stationary equipment provisions of fluorinated greenhouse gases regulations.


SafePQQ goes beyond Health and Safety showing our clients our commitment to ethical business practice, through a series of compliance questions covering GDPR, Finance, Modern Slavery, Building Information Modelling, Quality Management, Right to work, Environment, Anti-bribery and Equality.

Our People

Simon Gray

Founder of GMS and Managing Director, Simon Gray began his career as an apprentice engineer some 27 years ago, working predominantly at Heathrow Airport. Rising up through the ranks to Senior Engineer then into Project Management whilst undertaking numerous training courses associated with working in such a high profile environment to include H&S, Fire Training, Building Services to HND level, Air Conditioning and Refrigeration, Electrical Installation and finally studying Business at Thames Valley University. After 10 years’ service moving onto HM Air Cooling to develop his Project Management skills within the retail sector. Following a 5 year stint and takeover of HMAC, Simon departed and went on to start Gray’s Mechanical Services setting up an office at home.

Vanessa Gray

Finance Director for GMS has worked in accounts for over 20 years for various local businesses and after a brief spell trying her hand at Quality Management joined us in 2014 to complete the family overseeing all the finances, HR and Health and Safety aspects

Philip Gray

Service Manager at Gray’s Maintenance has been in management for over 30 years running various businesses and franchises and has been with GMS since the start, firstly on the tools and now based at HQ, he is an asset to the day to day running of the office bringing his years of experience and many a tale.

Callum Gray

Contracts Manager. Callum joined the business the beginning of 2020, he has quickly learnt the ropes and is an important member of the team. He has also undertaken extensive training in AutoCAD enabling Design drawings and As Installed drawings to be produced for projects undertaken.

Our history

Gray’s Mechanical Services was formed in 2010 by Simon Gray and has been positively trading since formation. Provisionally the company was formed to undertake the design, supply and installation of mechanical services across the retail and commercial sectors. In 2017 due to the growth of the preventative maintenance arm of the business Gray’s Maintenance Services was formed to differentiate between the two disciplines and ensure full focus from the separate companies to serve our clients needs.

Want to find out more about what we offer?

We’re here to help you plan, design and deliver your next project.