Barbados Quest

Barbados Quest, released in the United States as Murder On Approval is a 1955 British crime drama film directed by Bernard Knowles.
Plot.
An American philatelist pays £10,000 for what he thinks is a rare postage stamp. After he becomes concerned of its authenticity he employs detective "Duke" Tom Martin (Tom Conway) to investigate.
Critical reception.
"TV Guide" noted "An inept mystery."