William Borthwick (14 June 1879 – 16 December 1956)[1] was a British Liberal Party politician, Army Captain and Barrister.

[2] He was the son of Sir Thomas Borthwick, 1st Baronet[3] and Letitia Mary Banks.

They had four children, including a son William Jason Maxwell Borthwick.

[1] He gained the rank of Temporary Captain in the service of the King's Royal Rifle Corps.

[3] At parliamentary elections he contested, as a Liberal party candidate North Dorset four times; He did not stand for parliament again.