Gloag also has investments outside Stagecoach Group with her brother, including bus builder Alexander Dennis (through her Highland & Universal Investments company) and a chain of petrol stations and other property interests through a shareholding in Moncrieffe Holdings.
When the signal stations were established in 1818–1819, it became the key link in the chain, passing signals from Highgate east to Moncrieffe on the cliffs of the St. John/St. Philip border, and north to the Cotton Tower, Grenade Hall and Dover Fort (and vice versa).