Question: Who wrote a novel based on the LGBT-related film staring Robert Stephens and Colin Blakely ?

text: List of LGBT-related films of 1970
Films

This is a list of lesbian, gay, bisexual or transgender-related films released in 1970. It contains theatrically released films that deal with important gay, lesbian, bisexual, or transgender characters or issues and may have same-sex romance or relationships as a plot device.
Title Director Country Genre Cast Notes
The Boys in the Band William Friedkin United States Drama Kenneth Nelson , Leonard Frey , Cliff Gorman , Laurence Luckinbill , Frederick Combs , Keith Prentice , Robert La Tourneaux , Reuben Greene and Peter White Screenplay by Mart Crowley , based on his play of the same name ; one of the first major American motion pictures to revolve around gay characters
The Christine Jorgensen Story Irving Rapper United States Drama Joan Tompkins , John Hansen
The Conformist Bernardo Bertolucci Italy West Germany France Drama Jean-Louis Trintignant , Pasquale Fortunato , Stefania Sandrelli , Gastone Moschin , Dominique Sanda , Enzo Tarascio , Fosco Giachetti , José Quaglio , Pierre Clémenti , Yvonne Sanson , Milly , Giuseppe Addobbati , Antonio Maestri and Christian Aligny Based on the novel of the same name by Alberto Moravia
Daddy , Darling Joseph W. Sarno Denmark United States Sexploitation Helli Louise , Gio Petré , Ole Wisborg
The Dark Side of Tomorrow Jack Deerson , Barbara Peeters United States Drama , romance Elizabeth Plumb , Alicia Courtney , John Aprea , Marland Proctor and Wayne Want Re-released in 1975 as Just the Two of Us
Dorian Gray Massimo Dallamano Italy West Germany United Kingdom Horror , thriller Helmut Berger , Richard Todd , Herbert Lom , Marie Liljedahl , Margaret Lee , Isa Miranda , Eleonora Rossi Drago , Maria Rohm , Stewart Black and Beryl Cunningham Based on the novel novel of the same name by Oscar Wilde
Entertaining Mr Sloane Douglas Hickox United Kingdom Comedy Beryl Reid , Peter McEnery , Harry Andrews and Alan Webb Based on the play of the same name by Joe Orton
Gods of the Plague Rainer Werner Fassbinder West Germany Drama Hanna Schygulla , Margarethe von Trotta , Harry Baer , Günther Kaufmann , Carla Egerer , Ingrid Caven , Jan George , Marian Seidowsky and Yaak Karsunke
Golden Eagle Mitr Chaibancha Thailand Action Mitr Chaibancha , Petchara Chaowarat , Ling Fan , Chuen Chan , Chat Chayaphum , Chuan Chen , Hao Chen , Ti-Ko Chen and Yi-Hsiung Chi Sub-plot features a gang of kathoey as criminals , with a cross-dressing police detective trying to infiltrate them ; Chaibancha fell to his death while filming the stunt for the final scene
It Is Not the Homosexual Who Is Perverse , But the Society in Which He Lives Rosa von Praunheim West Germany Documentary , Drama Berryt Bohlen , Bernd Feuerhelm , Ernst Kuchling and Norbert Losch
The Kremlin Letter John Huston United States Crime , drama  Based on the novel by Noel Behn
Little Big Man Arthur Penn United States Western Dustin Hoffman , Faye Dunaway , Chief Dan George Based on the novel of the same name by Thomas Berger
Myra Breckinridge Michael Sarne United States Comedy Raquel Welch , Rex Reed , John Huston , Mae West , Farrah Fawcett , Roger C. Carmel , Roger Herren , George Furth , Calvin Lockhart , Jim Backus , John Carradine , Andy Devine , Grady Sutton , Robert Lieb , Skip Ward , Kathleen Freeman , B.S . Pully , Buck Kartalian , Monte Landis , Tom Selleck , Toni Basil , Dan Hedaya and William Hopper Baed on the novel of the same name by Gore Vidal
Monique John Bown United Kingdom Drama David Sumner , Joan Alcorn , Sibylla Kay , Nicola Bown , Jacob Fitz-Jones , Davilia O'Connor , Carol Hawkins and Howard Rawlinson
No desearás al vecino del quinto Ramón Fernández Spain Italy Comedy Alfredo Landa , Jean Sorel , Princess Ira von Fürstenberg , Isabel Garcés , Margot Cottens , Adrián Ortega , Annabella Incontrera , Guadalupe Muñoz Sampedro , Franco Balducci and Malisa Longo
The Private Life of Sherlock Holmes Billy Wilder United Kingdom Adventure , comedy , crime Robert Stephens , Colin Blakely , Geneviève Page , Christopher Lee , Irene Handl , Clive Revill , Tamara Toumanova , Stanley Holloway , Mollie Maureen , Catherine Lacey , James Copeland , Jenny Hanley and Alex McCrindle
Something for Everyone Harold Prince United States Comedy , crime Angela Lansbury , Michael York , Anthony Higgins , Jane Carr , Heidelinde Weis , Wolfried Lier , Despo Diamantidou , John Gill , Eva Maria Meineke , Klaus Havenstein and Walter Janssen
Tell Me That You Love Me , Junie Moon Otto Preminger United States Comedy , Drama , romance Liza Minnelli , Ken Howard , Robert Moore , James Coco , Kay Thompson , Fred Williamson , Ben Piazza , Emily Yancy , Leonard Frey , Clarice Taylor , James Beard , Julie Bovasso , Gina Collens , Barbara Logan and Nancy Marchand Based on the novel of the same name by Marjorie Kellogg
Trash Paul Morrissey United States Drama Joe Dallesandro , Holly Woodlawn , Jane Forth , Michael Sklar , Geri Miller , Andrea Feldman , Johnny Putnam , Bruce Pecheur and Diane Podlewski
Valerie and Her Week of Wonders Jaromil Jireš Czechoslovakia Drama Jaroslava Schallerová , Helena Anýzová , Petr Kopriva , Jirí Prýmek , Jan Klusák , Libuse Komancová , Karel Engel , Alena Stojáková and Otto Hradecký Based on the novel of the same name by Vítězslav Nezval