| Honorific Prefix: | Air Chief Commandant |
| Dame Mary Welsh | |
| Office: | Director of the Women's Auxiliary Air Force |
| Term Start: | 1943 |
| Term End: | 1946 |
| Birth Name: | Ruth Mary Eldridge Dalzell |
| Birth Date: | 2 August 1896 |
| Birth Place: | Claughton, Birkenhead, England |
| Death Place: | Farnborough, Hampshire, England |
| Allegiance: | United Kingdom |
| Branch: | First Aid Nursing Yeomanry Auxiliary Territorial Service Women's Auxiliary Air Force |
| Serviceyears: | 1918–1919 1937–1946 |
| Rank: | Air Chief Commandant |
| Commands: | Women's Auxiliary Air Force |
| Battles: | First World War Second World War |
| Awards: | Dame Commander of the Order of the British Empire Territorial Efficiency Decoration |
Air Chief Commandant Dame Ruth Mary Eldridge Welsh, (née Dalzell; 2 August 1896 – 25 June 1986) was the second Director of the British Women's Auxiliary Air Force (WAAF), from 1943 to 1946.
Ruth Mary Eldridge Dalzell was born in Claughton, Birkenhead, the daughter of William Robert Dalzell[1] and Ruth Mary Frances Annie Elizabeth Goldsworth Kirkpatrick Dalzell. Her father was a doctor.[2]
During the First World War, Mary Dalzell went to France as an ambulance driver in the First Aid Nursing Yeomanry, from October 1918 to June 1919.
As an Air Force wife, she travelled with her husband. In 1937, she joined the Emergency Service, and in 1938 the Auxiliary Territorial Service (ATS), the women's branch of the British Army.[3] In 1939 she was promoted to the senior commandant, based in London; she was transferred later that year to the Women's Auxiliary Air Force (WAAF). She served as inspector-general from 1942 and succeeded Katherine Jane Trefusis-Forbes[4] to become the second Director of the WAAF, from October 1943[5] to November 1946.[6] In this work, she toured WAAF locations abroad, including Belgium, Italy, and India.[7]
Mary Dalzell married William Lawrie Welsh, an officer in the Royal Air Force, in 1922. They had a son, Michael, born in 1926. Her husband was knighted in 1941, making her Lady Welsh. The Welshes divorced in 1947, and she moved to Odiham, Hampshire. There she was active in historic preservation as president of the Odiham Society. Mary Welsh died, aged 89, on 25 June 1986, in Farnborough.