Increased memory_limit in php.ini from 8Mb to 16Mb & restarted wampserver: bbPress installation then worked perfectly.
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; Resource Limits ;
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max_execution_time = 30 ; Maximum execution time of each script, in seconds
max_input_time = 60 ; Maximum amount of time each script may spend parsing request data
memory_limit = 16M ; Maximum amount of memory a script may consume (8MB)
Many thanks for your very impressive software and excellent support :>)