I thought the last "offical" steam train to leave from paddington went to birkenhead !.
The last through train from Paddington to Woodside ran on Saturday, 4th March 1967. This was a special organised by Ian Allan, but it was diesel hauled out of Paddington as far as Banbury, then steam hauled by 'Clun Castle' to Woodside.
The last regular passenger steam train from Paddington was on 11th June 1965, this was also hauled by 'Clun Castle' and was timetabled as London Paddington to Banbury.