This material has already been aired several times, both here and on the TMP thread Susan mentioned. Perhaps you didn't make the connection, Tom.
I had been meaning, as a last footnote to these proceedings, to share Georges Cadoudal's final letter to Guillemot Valentin, his contact among the party of Chouans billeted in Romsey after escaping from Brittany. That is to say, it might be worth quoting the final passage of that letter, which is relevant to the fiction that Cadoudal had been runnning a 'guerilla training camp' in the small market town just inland from Southampton.
Before embarking at Hastings in August 1803, Cadoudal wrote:
"Encore une fois, mon cher Valentin, faites monter constamment
chevalles hommes propres a notre entreprise, qu'ils galopent
vivement, qu'ils sautent les fosses, qu'ils'se chargent; enfin eduquez-
les de maniere a ce que dans un mois ils puissant lutter contre un
homme a cheval. Toutes vos cavalcades doivent autant que pos-
sible se faire dans le bois enfre Rumsey et Winchester, afin que
cela ne soit nullement public."
'Piéces Justificatives', Georges Cadoudal Et La Chouannerie pp.453-54
In other words, on the point of departing for France, Cadoudal was urging that a group of men should be selected, men who Guillemot deemed suitable for their projected mission although not to the extent of having any great riding ability, and that these as yet unspecified individuals were to improve their riding skills so as to be able to tackle Bonaparte's escort of light cavalry; and they had a month in which to do this. In Cadoudal's estimation, that goal would be best achieved by riding at speed and jumping ditches, in a discreet corner of the wooded high ground between the valleys of the Test and the Itchen.
This recommended riding practice is the extent of 'training' of which there is any evidence, riding practice that had not begun when Cadoudal sailed to France for the last time, and which, for all we know, may never have taken place. Whether this letter was the pretext for Cronin's reference to "guerrilla training camps" we can't tell, since, as has already been discussed, that author's notes do not enlighten us as to what material may have inspired his assertion.