Mark Osborne is one of the pseudonyms used by John William Bobin, born in the fourth quarter of 1889 in the Lewisham district of London and died in the second quarter of 1955 in the district of Rochford, Essex. He was aged 45. As Mark Osborne he wrote nine thrillers, all of them featuring the detective Sexton Blake. His first title was 'The Boarding House Mystery' (1931) and the last The Dog Track Murder (1934). He also wrote thrillers under his own name and using the pseudonym John Ascott. Under his own name he wrote 45 titles, all of them once again featuring the detective Sexton Blake. His first title was 'The Shadow of His Crime' (1915) and the last 'The Secret of the Surgery' (1929). As John Ascott he wrote five thrillers between 1928 and 1931. As Mark Osborne his titles were: The Boarding House Mystery (1931) The Consulting Room Crime (1932)* Dead Man’s Bag (1932) The Kennels Crime (1932) The Great Art-Gallery Crime (1932) The Mystery of the Lost Legionnaire (1933) The Stables Crime (1933) The Case of the Crook Iron Master (1934) The Dog Track Murder (1934) *This title was also reissued under the title The Consulting Room Mystery in 1940. Footnote: Whilst the year of birth and death is correct, the actual dates of birth and death are unknown, although the quarter in which he was born and died is known. So that the dates can remain in this record, the first date of each relevant quarter has been used.