Clockwise from 4 run three titles (6,2,3,6,7,9,3,4,3,4,5) linked with X who won a 21 of 8s. 29 is a fourth such title. Solvers must shade the three clued lights that combine to form an anagram of X (two words). 29th August is doubly significant.
 

Across

 
9    Sea lion’s grandchild swallowing salt (5)
10    Painter shed tears about China (5)
11    My railway truck (5)
12    Sewers trimmed cape Caesar shortened thrice (7)
13    Vent abuse together with spitfire (10, two words)
15    Keeper trailing black bear (5)
18    Alien badgers king and emperor (and the other folk) (8, two words)
19    Enlightenment transformed aristo (6)
24    Old romance clown talked...