The Lambkins aka Loudons, Crawfords and Campbells all resided in Auchruglan Castle before that edifice was reduced to a ruin in the 14th. C.. The reason for the feud between the Kennedys and the Loudons [so called by title and not by family name] was that the latter both Crawfords and Campbells were Sheriffs of Ayr, now Ayrshire, Shire being derived from Sheriff, an honour that the Kennedys, as one of the oldest indigenous families in what became Ayrshire claimed should be theirs.

The Campbell, Sheriff of Ayr and Earl of Loudon, highest dignitary in the County/Shire understandably abandoned the site at Auchruglen and built what was the first Castle of Loudon on the opposite side of the river Irvine. This would no doubt be the finest Castle in those parts and dare I say it would be counted the Prime castle of any in those parts.
If anyone can produce a better explanation for the name let's have it.
As regards the grave of Lambkin, my copy of the ballad states he was wrapped in lead and melted as was a Lord Soulis in the borders.

Finding a date for the burning of Auchruglen Castle in the 14th. C. is proving to be a bit of a strain on my eyesight as some of the tomes being consulted have rather small print.

There are no Lambkins in the local telephone directory, plenty of Lambs with a not inconsiderable no. of Norman French Agnews.

Honest labour to obtain a living is no disgrace, even for one having aristocratic connections and indeed one of our Scots Earls had a glovers business in Edinburgh and after making and supplying his peers with the gloves which were part of the dress code at the time he would appear with them and cast his vote as a Peer of the Realm.