Troughs with an "AND rather than a "&" in the inscription

On most troughs that contain the "Metropolitan Drinking Fountain and Cattle Trough Association" name as an inscription the "&" character is used. For an unknown reason some troughs, without any obvious pattern, contain the word "AND" in full.

Clapham Common

Tottenham High Road

Hyde Vale

Bostall Hill

Lambeth Road

Tunbridge Wells

Stonehouse

New Haw (now missing)

Lynton

Southwark