The Speedway Star of the time(19th May 1956) has a report which states that Sidlo was involved in the crash. Bishop and Kapala were out front when Sidlo fell in front of Raniszewski.
Initially the Poles had refused to ride owing to the safety and surface of the track, but eventually agreed primarily because a World Championship Round was scheduled for the same track later in the year.
The following week has a two page article on the first Polish Tourist team to the UK and describes how Raniszewski was due to have been part of the squad.