Possible Clues:

• Bumpkin would appear extremely dense in test
• Bumpkin, dim, wasting time
• His top score was four-hundred and five in nineteen eighty-eight
• Graeme, who once scored four zero five not out
• Yokel (American)
• Yokel's greeting to old silk turning up
• Graeme --, former England cricketer
• Bumpkin is dull-witted, no leader
• Bumpkin is stupid, wasting time
• Hayshaker