Converged network and controls for a government estate

Client: Major UK government organisation (anonymised at the client's request)

The brief

A multi-tenant government estate where the BMS estate had drifted onto the same network as the corporate IT fabric over a decade. The security team wanted IEC 62443 SL-2 conformance evidence without an open-ended engineering programme.

Our scope

• Zone-and-conduit map of the current estate; target-SL assignment per zone.
• Network segmentation design separating operator, controller and field zones.
• Conformance pack documenting the SL-2 controls in place, with traceability to 62443-3-3 clauses.
• Witnessed segmentation testing post-deployment.

Outcome

20-page SL-2 conformance pack accepted by the client's security function. Engineering scope held at 18 months and £4.2m — meaningfully below the alternative quote that took the whole standard literally.