About1Derek on the slopes of Mount Eiger, Switzerland

D-Four was formed in late 2011 to meet the growing requirement in the public and private sector for experienced, independent, unbiased protective security guidance for high-value sites and assets.

The company was formed by Derek McDonald who was until 2011 employed as Senior Protective Security Advisor, with the Protective Security Advisory Team (PSAT), Security Services Group (SSG), MoD.

In his former role, Derek headed the Security Services Group Advisory team for Scotland and NI, advising on appropriate protective security measures and acting as intelligent client for the very Highest Value Military, CNI, Royal Residences, NHS and Nuclear sites throughout the UK. In the course of these duties, liaison with HOSDB, CPNI, Police and other agencies vested with security and counter-terrorism responsibilities was routine.

D-Four is not affiliated to any equipment suppliers or installation companies. Our aim is to provide clear, independent, unbiased advice on security threats and counter-measures, based on CAPABILITY. This ensures unbiased advice for clients. Our advice is based on the standards and approach demanded in JSPs 440 and 480 and recommendations for equipment, where requested, will centre on proven equipment from the SEAP CSE or that in current industry use. D-Four is currently carrying out security consultancy work for the NHS, as well as a significant Government project and other large clients.

–     34 years in UK MoD
–     Headed Project Management and Delivery for NW Europe
–     Background in SCIDA, TEMPEST, on-line cryptography and telecoms

–     ONC Electrical and Electronic Engineering
–     B.Sc. in Systems Management
–     Cranfield MBA

For a confidential discussion call 00 44 7704 421150

Why Choose D-Four?


D-Four staff have worked to protect some of the highest value sites and assets in the UK. Government buildings, military sites, CNI and nuclear sites are only some of the sites we have given advice on. We have also aided partner companies in designing security solutions and systems for high net worth private residences.

D-Four are familiar with the requirements of British Standards, JSP 440 and CSE listed security measures – both prerequisites for compliant Government solutions.


D-Four guarantee discretion and confidentiality. Consultancy work on behalf of clients is done on a “need to know” basis and we are happy to commit to “Non Disclosure Agreements” (NDA’s) to assure commercial and security safety. Staff are currently DV cleared and able to work on Government sites and projects which demand the highest security clearances and procedures. Currently, D-Four are engaged in security work for Architectural, Government, NHS and Very High Net Worth clients.



With experience in the use of fence-mounted microphonic systems, in- ground “leaky feeder”, microwave, laser and others, we can specify the most appropriate technology.



D-Four have experience in specifying and procuring automobile on-board monitoring. In the event of attempted theft or hi-jack, systems will send alarms, real-time video and audio feeds to monitoring stations. The systems can also be used in a static setting (buildings, sentry posts, shops), if required.


D-Four will recommend appropriate “hard” boundary solutions for clients. These can range from lightweight fences which simply “demarcate” boundaries, to high security fences suitable for military, nuclear or prison sites. We can also specify appropriate gates and barriers including automatic gates, rising barriers and “pop-ups”.


D-Four can design and specify day/night CCTV or Thermal Imaging solutions to ensure correct coverage of client sites. Systems are specified to “ROTAKIN” or “HOCAST” criteria, ensuring usable, clear images for operators in Control Rooms.


D-Four can recommend appropriate IDS solutions for internal security. Motion Detection, Infra Red (IR), window and door sensors.