Jerry, thank you so very much for coming in, and especially for entering this fantastic Stirling example! and sharing the corroborating example from auction detail.
As you note, your hilt does seem to be from the 2nd quarter 18thc and pretty much mirrors examples signed by Walter Allen, so certainly likely from his shop or closely associated. Stirling hilts seem to typically be pretty much free form rather than adhering to the shield and bars systems of Glasgow. The round bars are of course key to Stirling examples.
Well noted on the Drury blade also as by third quarter 18th he had taken over for Jeffries, who he had partnered with in London since mid 18th or slightly earlier. They were producing swords for British army, mostly munitions grade hangers and basket hilts. It seems that Drury, like Jeffries were primarily cutlers, and assembled swords so blades were probably imports but as yet unclear on their source.
After Culloden (1746), while weapons were proscribed for Highlanders, the officers of Highland units were still entitled to heirloom swords and blades and it seems likely this pairing came out of these circumstances. Many basket hilts were 'taken down' rather than being given up, and the blades cut down for dirks, which as utility knives were still permissable.
The 'fluer de lis' element is commonly referred to as the 'rams horn' in Highland hilt nomenclature, which is likely to simply be an eponym rather than any symbolic significance. This is like the case with the 'S' element in many hilts which is simply an aesthetic structural element and does not signify "Stirling"; Scotland or Stuart as many have suggested.
While I have searched for many years to find such imbued symbolism in the motifs and elements of these hilts, the only examples that can be definitely aligned are thistle, oak leaf and a number of 'secret' Jacobite symbols with many still debatable.
On the hearts.....jury's still out
Yours is a magnificent example of a Stirling hilt, and with notable history with possible Culloden period use, and later remounting of hilt into English blade suggesting further service later in the century.
Outstanding! and thank you again.
I hope others will join, and I welcome any observations on my comments..this is all a learning curve and I only suggest what I have understood from research thus far.