Inscribed "in celebration of the diamond wedding of Diana and Dennis Tucker 9th August 2016".
 
Technically the progression is 2,3,1,4 - but the former 1st couple dance down to 4th place as a new top couple starts which effectively gives a 2,3,4,1 progression.

The symbolism is: 1-8 meet & greet; 9-16: down the aisle; 17-24: tying the knot; 25-32: 60th anniversary.