Seely was born in 1920. He was the eldest son of the 1st Baron Mottistone from his second marriage to the Hon. Evelyn Izme Murray daughter of Montolieu Oliphant-Murray, 1st Viscount Elibank and 10th Lord Elibank. He was a grandson of Sir Charles Seely, 1st Baronet. He was baptised with Winston Churchill and the then Duke of Cornwall (subsequently Edward VIII, and then later HRH Duke of Windsor) as his godparents.
He was Lord Lieutenant of the Isle of Wight from 1986 to 1995 and the last Governor of the Isle of Wight from 1992 to 1995, where the Seely family have played a prominent role since the 1850s. He was Chairman of the Bureau of Applied Sciences from 1987 to 1991 and was made an Honorary Doctor of Literature by Bournemouth University in 1993 and a Commander of the Order of the British Empire in 1984. He was also a member of The Royal Yacht Squadron. He died on 24 November 2011. He was succeeded by his eldest son Hon. Peter John Philip Seely born 29 October 1949, who is a godson of Prince Philip, Duke of Edinburgh.
- "David Peter MOTTISTONE Obituary: View David MOTTISTONE's Obituary by The Times". Announcements.thetimes.co.uk. 24 November 2011. Retrieved 29 November 2011.
- "Lord Mottistone obituary". Daily Telegraph. Retrieved 26 September 2018.
- Obituary in the Daily Telegraph: https://www.telegraph.co.uk/news/obituaries/military-obituaries/naval-obituaries/8973893/Lord-Mottistone.html
Sir John Nicholson
| Lord Lieutenant of the Isle of Wight
Sir Christopher Bland
|Peerage of the United Kingdom|
Arthur Patrick William Seely
| Baron Mottistone
Peter John Philip Seely