Sorry David
Kilmarnock was famous for the manufacture of Blue Bonnets otherwise known as "Kilmarnock Cowls". This was the ubiquitous hat of lowland Scots and effectively more the trademark of the lowland commoner than the aristocratic kilt. This is the garb that we should be wearing to the Highland Gatherings
The bonnet is the one that has been made famous in Tam o' Shanter by Burns.
David de Manitoba or Barry Robertson would be of greater assistance than I on this matter as they are "much closer to the ground".
The fashion thing of the kilts meant that they have only been worn on ceremonial occasions and not as common wear therefore the Caldwell's as miners, weavers, small farmers and labourers would have little time for the kilt - more especially given the lowlander's feeling of separateness from the highlands.
I note that Paisley and Kilbarchan (also Caldwell Country) rather than Kilmarnock were the centres when many tartans were woven. This was their trade and any cloth might be woven that was in demand and readily sold.
Kilmarnock is otherwise famous world wide for Johnnie Walker whisky, BMK (Blackwood & Morton Kilmarnock) fine axminster carpets, Glenfield & Kennedy - hydraulic engineers and of course - Joseph Caldwell then Thomas Caldwell and Adam Caldwell (all Kilmarnock based soft drink manufacturers).
Any US servicemen based at Prestwick during WWII are more than likely to have refreshed on Thomas Caldwell Soft Drink as he was the sole soft drink supplier for the south west of Scotland during the war-time austerity measures.