Edward Randulph Sladen was born in Theddlethorpe, Lincolnshire, England on 28 September 1878. In the 1911 England & Wales Census his occupation is given as architect's assistant he is described as an independent architect and was living in Beaconsfield, Buckinghamshire.
Drawings and plans of a house designed by Sheppard & Harris are illustrated in Designs for One Hundred Ideal £1,000 Houses. Being copies of the hundred best designs entered in the 1912 Daily Mail Architects' Competition (1912 p.92).
Although Sladen is listed as an architectural student in the 1904-1905 R.I.B.A. Kalendar, he appears not to have formally qualified as an architect or to have been a member of the Society of Architects or the Royal Institute of British Architects.
His address was given as Bourne End, Buckinghamshire in 1904; Park Lane, Amersham Road, Beaconsfield, Buckinghamshire in 1911 and Salisbury House, High Street, Beaconsfield, Bucks. 1912. He died in Blandford, Dorset on 15 July 1942.