Mary Beatrice Rundle CBE (10 August 1907 – 29 September 2010) was the first officer in charge of the Women's Royal Naval Service (WRNS) at Portsmouth during World War II.

She was educated at Sheffield High School for Girls, where she won an open scholarship to study at Harrogate Ladies' College.

As World War II approached, Rundle was commissioned into the WRNS and undertook officer training at the Royal Naval College, Greenwich.

[4] She was a justice of the peace for Aylesbury, Buckinghamshire, and a member of the Church of England's Advisory Council for Moral Welfare Work.

His brother was the medical superintendent at Aintree University Hospital, in Fazakerley, Liverpool, and his sister, Mary Snell Rundle, was the first ever secretary of the Royal College of Nursing.

He received the Distinguished Service Order (DSO) for his conduct in the Battle of Jutland,[7] and in 1918, he was awarded the Chevalier of the Legion of Honour.

[15] She married Robert Arthur Balfour, 2nd Baron Riverdale of Sheffield, on 1 September 1926 at Highfield Church, Southampton.

[16][2] However, she died after a short illness on 8 August 1928, aged 24, at Ropes, Fernhurst, the home of her father-in-law, Sir Arthur Balfour.

[17] By September 1932, Rundle was employed as personal secretary to Sir Anderson Montague-Barlow,[18]: vi  a former Minister of Labour, and best known for chairing the Barlow Royal Commission on the urban concentration of population and industry.

[23] She also served at HMS Calliope, then a training centre for the Royal Naval Reserve, located in Gateshead, Tyne and Wear, and HMS Daedalus, a shore airfield, located near Lee-on-the-Solent in Hampshire, for a number of naval air squadrons of the Fleet Air Arm.

[30]: 221  In April 1951, the work of the UK division was transferred to Lexicon Films Limited, an Encyclopædia Britannica affiliate located at 10 St Swithin's Lane, in the City of London.

[32] After 1951, Rundle joined Metal Box Company Limited, a large can and packaging manufacturer, as secretary to the managing director.

[34] She died on 21 June 1942,[35] and he married thirdly, Mildred Ellen Robinson, on 21 August 1944 at the parish church of Maresfield in the Wealden district of East Sussex.