Hi Liz,
The farm where Peter's William Waterson was robbed in Lonan is likely to have been Lhe Kerroo (two oo), Lhekerroo, Lhie Kerroo or Lheakerroo. (Likely because he was the only adult William W in Lonan in 1841.)
William Waterson was born in Malew so perhaps the robbers knew him from when he lived there, and knew that he had money?
I haven't been following where the pubs were, but if Mary's one was the closest I wonder whether there were Cain publicans there at the time?
Just had a look on the internet and the pub has a website, map, and contact number:
www.liverpoolarms.com/contact.htm
Perhaps you could contact them, Peter, and ask if they have any history of the publicans?
"The Liverpool Arms started life as a Coaching House and was known as the 'Halfway House', a term commonly used for watering holes between mid-distance between two communities. In our case, we are situated between Douglas and Laxey."
Sue