Strengthening the resilience of the UK's connectivity network
The UK's digital economy depends on a relatively small number of physical corridors connecting it to mainland Europe and the wider world. While the UK benefits from more than 60 subsea cable systems, resilience is determined not simply by the number of cables, but by the diversity of the physical routes, landing stations, terrestrial fiber corridors, and interconnection points they rely on.
On paper, the UK has a diverse and robust connectivity network. In practice, however, the concentration of traffic across a relatively small number of routes, landing stations, and hubs leaves it more vulnerable than its scale would suggest.
The UK's concentrated connectivity
The UK’s digital connectivity exhibits a compounding pattern of geographic concentration, moving from coastal landing points to highly centralised data hubs.
Once subsea cables reach shores, landing stations are concentrated in a handful of areas in the South West and North West of England. Just two modern commercially available cables, Exa Express and Amitié transit to the USA directly without transiting Ireland, another major pinch point for UK connectivity.
And once cables come ashore, they converge further on a small number of established clusters. London's Docklands egress routes, which carry large volumes of traffic to and from East London's data centre hub, for example, or Slough, home to Europe's largest data centre cluster.
From these hubs, the traffic moving between the UK and mainland Europe relies heavily on a trio of interconnected Internet Exchange Points (IXPs): London's LINX, Amsterdam's AMS-IX, and DE-CIX.
Breaking out of these deeply entrenched paths is incredibly difficult. Even when operators deploy new subsea or terrestrial routes, they rarely chart entirely new territory. Building out completely independent infrastructure is prohibitively expensive; it is far more economically viable to head towards regions that already possess the power infrastructure and fiber networks to support it.
While adding new routes can address network congestion, additional capacity doesn't necessarily protect against failure. Two cables that share the same hub, exchange, or landing station would both be impacted if that shared point suffers from disruption if other precautious measures and further diversity isn’t taken into the account.
Capacity doesn't define resilience
We've seen time and again the significant consequences a single incident can cause. In February 2024, when several undersea cables were severed in the Red Sea – one of the world's largest internet chokepoints – up to 70% of all traffic between Europe and Asia was disrupted.
Typically, damage is accidental, with fishing nets and ship anchors accounting for the vast majority of subsea cable faults. However, there's growing concern among UK lawmakers about the threat of deliberate sabotage. The location of almost every subsea cable is publicly available, and where cables cluster closely together, it would be relatively straightforward for a hostile actor to sever several at once, disrupting critical services and causing significant economic loss.
Building genuine route diversity
The UK doesn't simply need more cables. It needs new physical routes that avoid traditional transit points, land at alternative sites away from already crowded corridors, and connect through cities that are not already established connectivity hubs.
The principle is already being applied in several infrastructure projects. RETN's recently launched London–Brussels route, that was engineered to maximise physical diversity by using a different UK landing station, avoiding traditional Docklands egress routes, and creating an alternative path into mainland Europe. The objective wasn't simply to add capacity, but to reduce dependence on shared infrastructure.
Such choices may add cost and complexity to projects, but that's what it takes to build something that holds up during disruption. A network of routes that all start, stop, and end at the same points is neither diverse nor resilient.
