As M.R.D. Foot put it, opening Jones's own obituary [19 December 1997], "R.V. Jones was one of the main wizards during the secret war against Hitler, became a pillar of scientific education, and wrote some notable books." Jones was in a position to know.
As I got to know the Currans better, Sam never missed the opportunity to point out that Joan had indeed made a greater contribution than he had in his work previous to or during the Manhattan Project, and was a formidable scientist in her own right. In old age the way in which they looked after each other in their Glasgow Anniesland flat was rather sweet. When I was writing an obituary in a hurry of their friend Sir Nevill Mott [12 August 1996], I phoned Sam and he said, "I cannot talk to you until after half an hour; I'm doing my morning bathing of Joan's eyes."
Joan Strothers was born in Swansea, the daughter of an optician. Later at the Cavendish Laboratory and throughout her working life she had the reputation of extreme dexterity and being outstandingly neat and skilful in the deployment of equipment. She had the scientific equivalent of gardening green fingers which she would modestly attribute to her father's interest in her education. From Swansea Girls' High School she went up to Newnham College, Cambridge, on an open scholarship in 1934. Encouraged by the Newnham tutor A.C. Davies, after graduation she went to the Cavendish and was assigned to a group working under Philip Dee. In this group was the young Sam Curran with whom she had a romance which was to end in 58 years of supremely successful marriage.
On the outbreak of war the group went to Swanage and then to the Royal Aircraft Establishment at Farnborough, where other physicists included Philip Dee, Bernard Lovell and Alan Hodgkin.
R.V. Jones, in his book Most Secret War (1978), identifies the "two major possibilities" for their counter-measures against the Luftwaffe as "jamming and spurious reflectors". "Jamming," he writes,
appealed to me less, because it was cruder and moreover would jeopardise any aircraft carrying a jammer because it could be homed on by fighters carrying suitable receivers. Spurious reflectors would be simpler, and contained an element of hoaxing.
Spurious reflectors, to the development of which Joan Curran was so successfully to apply her technical dexterity, he explains as follows:
The phenomenon on which they depended was that of resonance. If a reflector is made of a simple wire or strip of metal of length equal to half the wavelength used by the radar station, it resonates to the incoming radio waves and re-radiates them to such effect that it is roughly equivalent to a whole sheet of metal whose dimensions are a square and which has sides equal in length to half a wavelength. Thus a few hundred such strips or wires would reflect as much energy as a whole Lancaster bomber.
Originally I suggested that wires should be suspended from balloons, because the long wavelengths that were usual in 1937 would require lengths of at least 10ft; but we found that the predominant wavelengths in the German radar that we had to counter were about 50cm, so each wire or strip need only be 25cm long, and could be made light enough to fall through the air at a slow rate, and thus remain active for many minutes.
They did not get the immediate go-ahead for the use of the reflectors, however. It was not until 1941, as their knowledge of German radar grew, that Jones persuaded Churchill's adviser Frederick Lindemann to allow trials. These were undertaken, in late 1941 and early 1942, under Robert Cockburn's direction at Swanage by Mrs Joan Curran. "Her results were all that we expected," Jones recalled,
and she tried various forms of reflector ranging from wires to leaflets, each roughly the size of a page in a notebook, on which, as a refinement, propaganda
could be printed. The form that we finally favoured was a strip about 25cm long and between 1cm and 2cm wide. The material was produced and made up into packets each weighing about a pound, and the idea was that the leading aircraft in a bomber stream would throw them out at the rate of one every minute or so, to produce the radar equivalent of a smokescreen, through which succeeding aircraft could fly. So much progress was made, after the years of delay, that by April 1942 enough material had been produced for it to be used by Bomber Command. It was given the code name "Window" by A.P. Rowe, the superintendent of [the Telecommunications Research Establishment] TRE.
The scheme was sanctioned by the chiefs of staff on 27 April 1942. It was the scattering of clouds of this foil by British bombers that confused the German gun-laying radar and provided a measure of protection against flak for the night raids of Bomber Command. Perhaps the greatest success of the work of Joan Curran and her team was its use where foil was dropped with great precision by the Lancasters of 617 Squadron, to synthesise a phantom invasion force of ships in the straits of Dover on the night of 5-6 June 1944. This kept Von Runstedt and his commanders unsure of whether the brunt of the Allied assault would fall on Normandy or in the Pas de Calais.
Early in 1944 Sam Curran was sent to the United States to work on the highly secret Manhattan Project. His wife helped him in his work on the invention of the scintillation counter - a device for measuring radioactivity that is still in use in many scientific laboratories.
However, during this period at Berkeley Radiation Laboratory, Joan gave birth to their first child, Sheena, who was to be severely mentally handicapped. When they returned to Glasgow after hostilities Joan and Sam Curran with a few friends set up the Scottish Society for the Parents of Mentally Handicapped Children, called Enable. It now has over 100 branches and more than 6,000 members. As a member of the Greater Glasgow Health Board, Joan championed the needs of the disabled; and as a Scottish constituency MP I know how much she did on the Council for Access for the Disabled, especially helping the disabled to get to university.
Among her other interests was the relationship between Strathclyde University (as, under the guidance of Sam Curran, the Royal College of Science and Technology became) and the Technical University of Lodz in Poland. The Polish 1st Armoured Division had been based in Scotland during the war and many stayed to be integrated into Scottish society. Joan Curran established funds to help them and we still have the Lady Curran Endowment Fund to help overseas students, particularly from Poland.
In 1987 Strathclyde awarded Joan Curran a degree of Doctor of Laws, which touched her greatly. Last year, permanently ill, she unveiled a plaque in the Barony Hall in Sam Curran's honour and she was told that the walled garden at Ross Priory, the University of Strathclyde staff club on Loch Lomondside, was to be named the Joan Curran Summer House. In later life, this distinguished scientist had played a wonderful role in welcoming the families of new staff to Strathclyde University. She played a major part in the outstanding success of Strathclyde.
Joan Strothers, physicist and charity founder: born Swansea 26 February 1916; married 1940 Sam Curran (Kt 1970, died 1998; three sons, one daughter); died Glasgow 10 February 1999.