Sir Humphrey pens a long blog post about a late Cold War Royal Navy ship — officially just a “diving support vessel”, but apparently much more capable — most naval fans may never have heard about:

HMS Challenger (K07) at Kiel, West Germany in 1985.
Photo by John Cook via Wikimedia Commons.

The story of HMS Challenger remains one of the most unusual of all post war Royal Navy vessels. Born in the late Cold War, she was in the eyes of the public a “white elephant” commissioned and never operationally used and sold after just a few years’ service at the end of the Cold War. She was to the few public that had heard of her, “the Warship that never was”. But revealing files in the National Archives tell a story of a ship that was designed to fill a range of highly secretive intelligence support functions and clandestine espionage activity that, had she been successful, would have made her perhaps one of the most vital intelligence collection assets in the UK. This article is about the untold story of HMS Challenger and why she deserves far more recognition than enjoyed to date.

The background of the Challenger story can be traced to the mid 1970s when the Royal Navy used the, by then positively venerable, warship HMS Reclaim to conduct diving support work. The Reclaim, commissioned in 1949 was the last warship in the RN to be designed and fitted with sails, that were occasionally used. Employed in diving support and salvage ops for 30 years, she was a vital asset for the recovery of crashed aircraft, support to diving and other assorted duties. But by 1975 she was also very old and out of date and requiring replacement (she paid off as the oldest operational vessel in the Royal Navy in 1979).

To replace her the Royal Navy developed Naval Staff Requirement 7003 and 7741, which were approved in 1976. These requirements set out the need for a replacement and the capabilities that were required. By this stage of the Cold War the world was a very different place both operationally and technologically from when HMS Reclaim entered service. There were significantly more undersea cables laid across the Atlantic, while the SOSUS network (a deep-water network of sonar systems intended to detect Russian submarines) had been delivered and expanded into UK waters in the early 1970s under project BACK SCRATCH. Additionally the Royal Navy had introduced a few years previously the Resolution class SSBN, which by 1976 had four submarines providing a Continuous At Sea Deterrent (CASD) with their Polaris missiles, as well as wider nuclear submarine operations. At the same time new technology was emerging including better diving capability, the rise of miniature submarines capable of both operating at immense depths and also the rise of rescue submarines for stranded nuclear submarines. Additionally technology had improved increasing the ability to recover items from the seabed.

When brought together this provided the RN with the opportunity to think afresh about how to replace Reclaim. The result was a set of requirements that were defined as follows:

The objective of NSR 7003 was to provide the Royal Navy with a Vessel and equipment capable of carrying out seabed operations. The requirement … is to find, inspect, work on and recover items on the seabed at all depths down to 300m with some capability to greater depths.

The specific missions for which the requirement was looking to cater for broke down into three main areas:

1. Inspection, neutralisation or recovery of military equipment, including weapons;
2. Operations in support of national offshore interests including research;
3. Assistance with submarine escape and rescue and with underwater salvage

This represented a significant leap forward compared to Reclaim, which was limited to diving at up to 90m in very limited conditions, and would have provided the Royal Navy with an entirely new level of capabilities.

The decision was taken to proceed with the requirement and Challenger was ordered in 1979 and commissioned in 1983. What then follows is a sorry story of a ship being brought into service and having practically everything that could go wrong, going wrong. This article will not go into any depth on the story of what failed, as to do so would be a lengthy story. Suffice to say that a combination of faulty equipment, manufacturing challenges, fires and other damages and the reality that technical aspirations were not matched by practical delivery in reality meant that Challenger never really became operational.

Used for a series of trials until the late 1980s to prove her systems and see if they would work, she struggled to achieve what was expected of her. She had some success recovering toxic chemicals from the seabed from a sunken merchant ship in the 1980s and then conducting other demonstrations, such as deep diving and supporting submarine rescue trials. But she never lived up to the expectations placed on her, and at a time when the costs required to get her to the level of capability were far too high, and the defence budget was under pressure at a point when the Warsaw Pact threat was rapidly collapsing, the decision was taken to pay her off as a failed experiment even before the wider Options for Change plan was announced. This much is widely known to the public, but what is nowhere near as well known is the missions that Challenger was intended to carry out. Had she been successful, it would have made a very real difference to RN capabilities.

Why did the Royal Navy seem so determined to make a success of Challenger for so many years, to the extent of throwing ever more money at her, given these problems? In short because the missions she was designed to do made it worthwhile. Files in the archives clearly show that beyond the public line of “research” she was designed to carry out exceptionally sensitive missions. Although the original Naval Staff Requirement focused on three areas, by the time she entered service, this had expanded to at least 9 (possibly more). These were:

1. Strategic Deterrent Force Security
2. Seabed surveillance device support
3. Nuclear weapon recovery
4. Recovery of security and military sensitive material
5. Crashed military aircraft recovery
6. Submarine escape and rescue operations
7. Salvage operations
8. MOD research and data collection for other than intelligence agencies
9. Miscellaneous operations in support of other government agencies

It can be seen that far from being just a diving support platform, Challenger was in fact an absolutely central part in providing assurance to the protection of CASD and ensuring the security of the nuclear deterrent and SOSUS. How would she have done this?

The files show that in the 1980s the UK had a different attitude to the US about protection of these routes due to geographic differences.