Reginald Saxton was a brave and radical doctor who matched his beliefs by his action, spending the early years of his medical career serving in the front line during the Spanish Civil War. There he transformed the often rudimentary surgical setting by developing a mobile blood-transfusion unit serving the wounded in the heat of battle.

Reginald Saxton, medical practitioner: born Cape Town 13 July 1911; married 1945 Betty Perkins (died 2000; one son, one daughter); died Worthing, West Sussex 27 March 2004.

Reginald Saxton was a brave and radical doctor who matched his beliefs by his action, spending the early years of his medical career serving in the front line during the Spanish Civil War. There he transformed the often rudimentary surgical setting by developing a mobile blood-transfusion unit serving the wounded in the heat of battle.

As a politically orientated doctor recently qualified from Cambridge and Bart's he was drawn to socialism and Communism following readings from Major C.H. Douglas's Social Credit (1924) and the series edited by C.R. Attlee "Labour Shows the Way". At Repton, under the discipline of that notorious headmaster Geoffrey Fisher (a future Archbishop of Canterbury), he said later, with that open laughter which so characterised him, "I couldn't somehow make contact with the Almighty."

Attending lectures at Transport House in London and studying economics at Reading Public Library persuaded him that only the left wing had the answers to the social inequalities of the Thirties. At Sidney Sussex, Cambridge, he found himself in a milieu of stimulating like-minded students for whom Communism represented a response to economic and political stagnation. For a year or so he worked for various medical teams at Bart's, including that of Geoffrey Keynes, and here he learnt the skill of blood transfusion.

At a meeting in August 1936 attended by barely 20 people and addressed by a Labour MP he volunteered to join the Spanish Medical Aid Committee; he left for Barcelona in September, and was sent to set up the First British Hospital, north of Aragon, "a muddy dirty old building with a perfectly useless drainage system". Frustrated by the internal politics, he returned to Barcelona and joined the 35th Medical Division Unit - attached to the French Battalion the XIV International Brigade. This brigade took the initial brunt of the Nationalists' push at the Battle of Jarama in February 1937. There 10,000 Republican soldiers died and Saxton set up hospital as an advance party in Villarejo de Salvanés.

It was the middle of the night and the circumstances were near-farcical, with a building being seconded to them, in the dark and in broken Spanish, by a mixture of threat and misunderstanding. That comic element rapidly vanished in the sleepless nightmare of the casualty clearing station. After two days Saxton crawled away to sleep under a pile of benches before being summoned back. In his letters home he writes, "One became almost an automaton . . . it was hard slog all the time . . . one long struggle to keep keeping on."

As recorded by Mike Cooper and Ray Parkes in their book We Cannot Park on Both Sides (2000), Saxton struggled with primitive techniques for transfusion and the lack of blood and instruments:

We had at that time no transfusion syringes and no satisfactory needles. I collected, however, two sets of instruments to enable me to dissect a vein and insert a cannula [a thin tube]. The blood was poured into a funnel and led by a rubber tube to a cannula.

With help from the Canadian Dr Norman Bethune, Saxton was provided with blood from Madrid and refrigerators on a van to get the blood around the casualty stations. Three great successes, he remembered, were two-way syringes, so that you could draw up from one donor arm and then inject into a recipient by means of a switch; the adaptation of the vital fridges to work on paraffin rather than petrol; and the developments of mobile laboratories for transfusion and medical work.

Up to 3,000 samples of blood were processed by these mobile labs, which included autoclaves, incubators, fridges and ovens. This was a major contribution to the medical welfare of the Republican war effort. At this time Saxton had also considered cadaveric transfusion, since this had been discovered as a possibility where patients had died very suddenly, but ethical, practical and infection issues prevented it.

The mobile medical units were set up in monasteries, olive groves, deserted factories, hotels and farmhouses, and in a huge cave above the banks of the River Ebro during one of the last battles at which Saxton was present.

Saxton's most famous patient was Julian Bell, son of the artist Vanessa Bell. This was at Villanueva de la Canada near the Escorial when the ambulance Bell drove came under attack by Nationalist bomber aircraft. Saxton had already noted how they were repeatedly attacked - bombed or strafed by fighter planes, often German or Italian. Bell sought shelter beneath the ambulance but a vast piece of shrapnel hit him in the chest, causing a terrible wound. He was brought into the clearing station and seen by Archibald Cochrane (then a medical student, but later the Professor at Cardiff after whom the Cochrane Library of medicine databases is named), who triaged him to hopelessly wounded.

Cochrane indicated to the orderlies to put him to one side. But he suddenly recognised the human face beyond the wound. Saxton was called, and the brilliant Spanish surgeon Moisés Broggi i Vallés, who examined him and retrieved from the gaping chest wound his wallet and passport which had been blown into the cavity. "His heart was visible through the wound," Saxton remembered:

I gave him a blood transfusion and dressed him again. But we realised we had to let him die and he died that night. When he saw me all he said was, "Thank goodness it's you." And I gave him morphine.

Many of these records come from the archive of Saxton's letters home and an interview he gave to the Imperial War Museum in 1984, but he also wrote articles for The Lancet about wartime blood transfusion and the provision of front-line medical care at a time when Britain was gearing up to meet the very same aerial and territorial enemies.

With other international brigade members he left Spain before the end of the war, but 60 years on, when Spain was a democracy again, he was invited back and made an honorary Spanish citizen.

During the Second World War he joined the British Army Transfusion Service and was present during the retreat through Burma - for his courage there he was mentioned in despatches.

Reggie Saxton worked in general practice from 1946 in Patcham in Brighton, and then from 1962 until 1976 with Dr Julian Tudor Hart in Glyncorrwg, a mining village in the Rhondda Valley. He retired to Lawton Ripe in East Sussex to tend a garden and work part-time in Brighton for the Family Planning Service.

He lost none of his zest and iconoclasm in recent years and was passionately against the war in Iraq.

Patrick Reade