"Skye Boat Song" was retrospectively written by Sir Harold Boulton, to an air collected in the 1870s by Anne Campbell MacLeod. The song was first published in "Songs of the North" by Boulton and MacLeod, London, 1884 and it does refer to "Bonnie Prince Charlie" and his escape to Skye in 1746. But as everything is "known" about the song there can be no ambiguity or debate about it.

On the other hand, as far as "Twa Recruitin' Sergeants" goes (The Jeannie Robertson Version), nothing is known about who wrote it - the fact that similar phrases appear and are used that occur in other songs means nothing, lack of originality, laziness, or simple coincidence could account for that, certainly means nothing as far as the specific question asked goes. The song is however about a specific regiment and it is about a specific time in the history of that regiment and in looking into the history of the regiment the period being referred to in the song can be identified. If it is a "recruiting song" why sing about the regiment being where it isn't?

Quite agree about the Haughs of Cromdale - it is complete and utter nonsense - As a song it is also complete and utter crap primarily because it is nonsense.

Likewise the faux "Bold Recruiting Sergeant" written in modern times but often introduced as a recruiting song from the days of Marlborough -

"A bold recruiting sergeant marched through the streets of Rochester
Bound for the wars in the low countries,
And he called as he marched to the beating of a kettle drum,
Who'll be a soldier for Marlborough and me?

Who'll be a soldier, who'll be a soldier
Who'll be a soldier for Marlborough and me
Who'll take the Queens shilling and wear a Scarlet Uniform
And fight in the Lowlands with Marlborough and me"

The tune is the same as for Andrew "Banjo" Patterson's Waltzing Matilda. The above was also re-jigged presumably by Tams for the Sharpe's Regiment episode.

There have been hiring fairs (Normally two a year) for centuries timed to coincide for events in the agricultural callendar where extra labour was required - biggest improvement in Scottish agriculture came with the Act of Union in 1707 and the arrival in Scotland of the "English Plough" which meant that the old and extremely inefficient "run-rig" system could be abandoned.

The system of recruitment described by you Jack ONLY applied to Clan based Highland Regiments - two exceptions amongst Highland Regiments were the Black Watch and the 71st who had, having been made up and taken onto the strength of the Army Lists, did not have any "local" recruiting base, so they had to rely on Recruiting Parties in exactly the same manner as the Lowland Scottish Regiments did and the English County Regiments did.

Oddly enough the Navy did not have too many problems recruiting as Prize Money served as incentive, likewise with the Army "plunder" served as a lure - obviously a regiment based in the West Indies or at home had little opportunity for "plunder" whereas one engaged on active service in Europe obviously did (even although the risks were a great deal higher) - so a recruiting song would advertise albeit in not so many words the fact that the opportunity for "plunder" was to be had.