Case Study: FTSE 100 | Modernising Legacy Infrastructure

Secure by Design:

How a FTSE 100 Organisation Future-Proofed Its Global Infrastructure

Case Studies | 17 June 2025

About the customer

Cloud-Smart Modernisation with Azure Arc

When a major FTSE 100 organisation identified a risk of falling out of compliance due to ageing infrastructure, they didn’t wait for a problem to escalate. Instead, they took a proactive approach. Their goal was not only to resolve the compliance challenge but also to deliver longer-term strategic benefits.

Testimonial

“

We knew we had to act before support deadlines became an operational risk. The goal was not just to fix the issue. It was to modernise in a way that set us up for the future

Senior IT Leader

FTSE 100 Organisation

The Challenge

Legacy Systems at End of Support

The organisation recognised a chance to turn ageing infrastructure into a catalyst for change. With many legacy systems, including older SQL Servers, nearing end of support and a renewal of endpoint security licences approaching, they saw the perfect moment to modernise.

Rather than wait for issues to arise, they acted early to reduce long-term costs, streamline operations across regions, and strengthen security. Their goal was to move quickly and confidently towards a more scalable, future-ready foundation without disrupting critical operations

Testimonial

“

What started as a compliance concern has become a model for global modernisation. We now have the control, cost-efficiency, and security to match

Senior IT Leader

FTSE 100 Organisation

The Solution

Cloud-Smart Modernisation with Azure Arc

Working in partnership with Microsoft and Telefónica Tech, the organisation launched a modernisation programme anchored in Azure Arc and Microsoft Defender. The initial phase focused on identifying and addressing a significant volume of legacy virtual machines and SQL Servers distributed across global operations.

A two-day, in-person design workshop defined the subscription structure, governance model, network architecture, and security policies. A full solution design document followed and became the blueprint for the Azure Arc rollout.

The project evolved into a centre of excellence model. This allowed the customer to scale the solution across thousands of servers globally while maintaining control, compliance, and consistency.

To support wider security goals, Microsoft Defender agents were deployed to replace their incumbent endpoint security licences. This aligned the organisation’s security tooling with Microsoft’s ecosystem and removed the need for a costly renewal.

The Outcomes

Significant Cost Savings and Improved Security

The organisation achieved significant budget savings in year one by replacing its existing endpoint security solution with Microsoft Defender. Thousands of users were protected through continuous patching and security updates, with a 99.4% deployment success rate.

The entire programme was delivered remotely by a small team of infrastructure and security specialists. It ensured compliance, mitigated risk, and created a more modern, secure, and centrally managed infrastructure.

With Azure Arc, the organisation also gained full visibility and control across its global server estate.

Savings

Significant savings in year one by replacing endpoint security with Microsoft Defender

1000s

1000’s of users protected with continuous patching and security updates

99.4%

99.4% deployment success rate

Testimonial

“

Telefónica Tech helped us move quickly but methodically. They understood the pressure we were under and brought the right blend of technical depth and strategic oversight.

Programme Lead

Cyber security & Compliance