Wildt & Kray,

Wildt & Kray (1903-), 15 Lensden Place, London, England. The Metro site covers W&K at metropostcard.com/publishersw.html, but it is wrong about the firm ending in 1916 as it advertised at the British Industries Fair in 1922 and 1929. Over time W&K used several different logos on the backs of cards, often with their name spelled out as well. The logo of W&K in an oval also appears on the front of some cards.
W&K 3132
W&K 3132 reverse
1922 advert, courtesy of Graces Guide.