"Proceeding along the yard, we stepped into the sampling and tasting room, situated at the end of the racking-house, where we tried one or two samples of the firm's brew. We we much pleased with the A.K. light bitter - a delicious drink, clean to the palate and well flavoured with the hop. All the ales brewed by the firm are known in the locality as "Walmer ales;" but the best known, perhaps, is the XX beer, which has a wide-spread reputation"
"The Noted Breweries of Great Britain and Ireland, vol. 4", Barnard, page 522.
The brewery in question was Thompson & Son at Walmer in Kent.
One thing is clear: Barnard regarded AK as a type of Bitter. I think we can trust his opinion, can't we?
I found another reference to Walmer Brewery AK
"The A.K.S. Bitter Ale will be found a particularly well flavoured tonic ale for general use; whilst the A.K. cheaper ale, and the celebrated India Pale Ale are both of excellent quality, clear and bright to the last. The latter as well as Pale Ale, Light Dinner Ale, Stout and Cooper are also obtainable in fine condition in screw topped bottles. The other productions of the Walmer Brewery consist of X, XX and XXX Ales of varying strengths, Double Stout and Porter; whilst the firm also bottle large quantities of Bass's Ales in the best possible condition."
"The Deal and Walmer Illustrated Guide", 1897.
AKS - that's a new one to me. I wonder what the hell that signified?