The pioneer class 57 is Freighliners 57001 which is appropriately named 'Freightliner Pioneer'.
It is seen here...just I should add...at Stratford on the 8th April 2004.
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Photo from James & Martin's Picture Collection Copyright 'Jampics' m.hawkes7@ntlworld.com 
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British and Foreign Railway Pictures <A HREF="http://jampics.fotopic.net/"> Jampics Fotopic.</a>