The political context of the event, coupled with a variety of curious circumstances (for instance, the Soviet agent Kim Philby was head of counter-intelligence for MI6 in Gibraltar at the time), immediately gave rise to numerous speculation that Sikorski's death had been no accident, and may have been the direct result of a Soviet, British, or even Polish conspiracy. Some modern sources note that the accident is not fully explained However, as Roman Wapiński noted in his biographical entry on Sikorski in the "Polish Biographical Dictionary" in 1997, no conclusive evidence of any wrongdoing has been found, and Sikorski's official cause of death is listed as an accident.