Two words form the name of a fictional 28, described by his creator as a ‘22A/31/26’. Remaining across unclued lights are associated with the first word and down ones with the second. Elsewhere, ignore an accent.
 

Across

 
1    Jackanapes swimming away from Jamaica belly-flops (8)
6    Taxmen laugh at seventy retired coppers (6)
11    Trifler enthrals former railman (10)
14    Old statesmen stands beside painter in food shop (8)
16    Some sham or phony rogue … (5)
17    … uttered marks (unacceptable) he had (7)
19    Most severe wind is in the Camargue (9)
23    Place with a birch tree (6)
24    Home Secretary boards train for subdistrict (6)
30    Duplicate data...