USC0029

Written evidence submitted by Jeremy Steventon-Barnes, former Chief Technology & Information Officer, EXA Infrastructure

Introduction

Since 2022, I have been employed as Chief Technology & Information Officer by EXA Infrastructure, which owns significant capacity across six transatlantic cables, of which three are wholly owned, including EXA Express, the shortest and therefore fastest connection between London and New York. EXA was created in late 2021 in a $2 billion private equity buy out led by US-based I Squared Capital. My employment with EXA terminates at the end of May, so I am making this submission in a personal capacity.

My 30+ year digital infrastructure and technology career began in BT’s Research Department at Martlesham Heath near Ipswich in Suffolk, where I worked closely with people who developed the first transatlantic fibre cable, TAT-8, which entered service in 1988. I contributed to the launch of BT’s first Internet service in 1994, and subsequently worked internationally in roles for BT, Cable & Wireless and Level 3 Communications, which I joined in 1998 as employee #7 in Europe. At Level 3, we delivered one of the first transatlantic fibre cables to be financed by a single company, known by its internal code name, Yellow (submarine), which entered service in 2000 and remains operational, now owned by Colt. I was responsible for the delivery of the first ever 10 Gbps transatlantic Internet link, which was carried on this cable, and my Level 3 colleagues have gone on to play significant roles in subsea cable development for major players, notably Google.

Since Level 3, I have exercised a variety of executive roles for different technology businesses and have maintained a close interest in subsea cables as the essential infrastructure which connects the global data centres upon which all Internet services rely. Last September, following work experience at EXA’s Network Operations Centre and Cable Landing Station in Dublin, my 18-year-old son Theo decided to explore UK subsea cable vulnerabilities for his Extended Project Qualification as he prepares to study for an Engineering degree, and this led me to review the state of UK connectivity with him.

My submission is based on this review, and I hope that it will be helpful to the Joint Committee on the National Security Strategy. I consider this submission to be within my professional competence as a Chartered Engineer and Fellow of the Institution of Engineering and Technology (originally founded in 1871 as the Society of Telegraph Engineers, and hence the appropriate Learned Society for subsea communications). My other qualifications include degrees in Physics from Durham, Telecoms Engineering from King’s College London, and an MBA from London Business School.

How might the UK’s reliance on undersea cables evolve over the next 10-15 years?

I wish to draw the Joint Committee’s attention to the following points:

• The UK’s 11 transatlantic cables are mostly low capacity and 20+ years old.
• Over the next 5-10 years, capacity is likely to be increasingly concentrated on just two recent cables, Grace Hopper and Amitié, which both land in Bude, Cornwall.
• For the first time in history, the UK is becoming reliant for restoration capacity on transatlantic cables from continental Europe.
• Ownership of transatlantic cable capacity is now highly concentrated amongst a small number of US technology companies (Google, Meta and Microsoft), making new transatlantic investments unattractive for traditional industry participants.
• The Channel Tunnel provides the primary high-capacity route for fibre connectivity between the UK and continental Europe, complemented by multiple recent high-capacity subsea cables primarily built by privately owned network operators.
• The handful of cables to Asia and Africa are not considered in this submission.
• Continuing developments in satellite technology may partly mitigate reliance on subsea cables over the long-term (eg to provide backup restoration capacity for critical communications), but subsea cables will remain essential to supply continued rapid demand growth.

UK transatlantic cable capacity

I am aware of Professor Ian Corden’s confidential report for the Department for Science, Innovation and Technology and have reviewed his summary slides from TechUK’s subsea cables summit in October 2024. Prof. Corden correctly identifies the transatlantic cables connecting the UK to North America, and I have updated some of his data points in the following Table from various sources including Telegeography and the Submarine Telecoms Forum Almanac.

Table: UK transatlantic cables to North America

* Prof. Corden’s slides list the combined capacity for the EXA South and North cables as 25 Tbps, whereas each 4-pair cable reportedly has this capacity (ie 50 Tbps total)

† Prof. Corden’s slides include the capacity of the Apollo South cable from France – US to total 64 Tbps capacity; the capacity of the UK-US cable is 32 Tbps

‡ Prof. Corden’s slides list Amitié’s capacity as 320 Tbps, which was its original design capacity of 20 Tbps on each of 16 fibre pairs. When deployed, this improved to 23 Tbps per pair, and the Submarine Telecoms Forum Almanac lists the capacity as 368 Tbps across 16 pairs from the US. The cable has 12 pair branches to each of the UK and France, yielding a maximum capacity of 276 Tbps to the UK.

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With nearly 75% of potential UK transatlantic capacity now concentrated across just two cables which both land in Bude, and limited prospects for new UK transatlantic cable investment in the foreseeable future, we must consider how future transatlantic traffic volumes could be rerouted were both cables to be damaged. The only option (and apparently the strategy being implemented by Google, Meta and Microsoft) will be to reroute UK transatlantic traffic via continental Europe.

As noted in the summary, reviewing the UK’s available capacity to continental Europe confirms the importance of the high-capacity fibre links through the Channel Tunnel, alongside several recent high-capacity subsea cables, listed in the following table.

Table: Mainland UK – continental Europe cables deployed since 2010

† Estimated 23 Tbps per fibre pair

* Colt completed a deployment of new high-fibre count cables through the Channel Tunnel in June 2023 under an exclusive 25 year concession which operates until 2036, providing very high capacity

‡ Source: IOEMA CTO Eckhard Bruckschen’s presentation at SubNets EMEA, London, February 2025

With over 8000 Tbps of potential cable capacity between the UK and continental Europe in addition to the Channel Tunnel route, there is clear potential to reroute the UK’s entire potential 850 Tbps of transatlantic via the continent were all UK transatlantic cables to be damaged.

The remaining question is therefore to review the available transatlantic capacity from continental Europe, as shown in the following table. In summary, in addition to the continental branches of Grace Hopper and Amitié, multiple other high-capacity transatlantic cables have been and are being deployed from the continent, providing good potential restoration options in the event of damage to UK transatlantic cables. However, at a whole European level, it must be recognised that transatlantic capacity is concentrated across a relatively small number of cables, presenting a significant risk of total loss of connectivity in the event of a coordinated attack by a hostile state actor.

Table: Transatlantic cables from Ireland / continental Europe to North America:

* Havfrue / AEC-2 comprises a main trunk of 6 fibre pairs between Denmark and the US, with a 6-pair branch to Ireland and a 2-pair branch to Denmark, with each pair designed to operate at 18 Tbps

‡ Amitié has16 fibre pairs from the US, with 12 pair branches to each of the UK and France, yielding a maximum capacity of 276 Tbps to each of the UK and France limited to a combined capacity of 368 Tbps

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Addressing some details arising from the table:

• Compared to the 11 cables to North America that land in the UK, 2 land in Ireland and 11 land in continental Europe
• One of the cables that lands in Ireland (AEC-2) also lands in both Norway and Denmark, so in total, there are 12 cables which land in Europe outside the UK
• While only 2 of the UK’s 11 cables are recent high fibre count systems (Grace Hopper and Amitié), 8 of Europe’s 12 cables are such recent systems, and these 8 include branches from both of those recent UK systems, suggesting that continental Europe benefits from much better long-term transatlantic diversity than the UK
• The total transatlantic capacity from Ireland is 186 Tbps, while the total capacity from continental Europe is at least 2140 Tbps (including 108 Tbps on Havfrue/AEC-2 also included in Ireland’s capacity), not counting Leif Erikson for which the capacity is currently unclear (but expected to be at least 250 Tbps)
• Considering the UK’s 850 Tbps transatlantic capacity, Ireland has insufficient capacity to provide diversity for the UK, but that there is good potential diversity via continental Europe
• In particular, since the UK’s two recent high capacity cables (Grace Hopper and Amitié) feature diverse branches to Spain and France respectively, it appears likely that failure of or damage to the UK branches of these cables could be mitigated by rerouting traffic to their continental European branches

Concluding remarks

As highlighted by multiple studies including the 2017 Policy Exchange report, subsea cables (and especially transatlantic cables) are highly vulnerable and difficult to protect. Other submissions will doubtless address these vulnerabilities and the challenges of achieving rapid repairs to multiple concurrent cable breaks.

The Joint Committee will already be aware that subsea cables are brought on-shore to Cable Landing Stations, which are typically small buildings often in remote locations. These buildings typically represent single points of failure and may lack the level of security and protection the UK government would usually expect for critical national infrastructure.

Fibre backhaul connectivity from Cable Landing Stations to large national data centres (eg in Slough and Docklands) typically benefits from dual route diversity but again may be vulnerable to attack both at cable chambers and intermediate transmission huts. (The potential disruption from such an attack was demonstrated in the Paris area during last summer’s Olympics).

6 March 2025