The film was originally known as
The Letter, with Pat Boone's signing announced in June 1963. It was to be produced for
Seven Arts-
MGM (eventually it would be made for Seven Arts-
Allied Artists). It was also known as
Strictly Personal. Filming began in
Dublin, Ireland, in July 1963. The schedule was for two months. (It was later ruled that the probably cause of the accident was the loss of control by the Proctor due to the effect of the slipstream caused by the C44.) Andrew Stone and his wife were among those with minor injuries. Pat Boone was not involved in the accident; he arrived in the country shortly afterwards. Questions were asked in
the Dail over the incident. Filming continued in Dublin for a number of weeks, with scenes shot at
Dublin Airport, the
Gresham Hotel, the Irish Life Building, Jury's Hotel and the Andrew Street Post Office. However, the government refused permission for any further low flying sequences. In August, the unit moved to London to complete the film. ==Release==