Robin is first seen in Troubled Blood in her Land Rover conducting surveillance on a man she and Strike nicknamed “Tufty” because of his “badly fitting toupee.” 

When Strike calls, Robin wishes she could see his face when she tells Strike about Tufty’s multiple families. 

“‘The hell’s he doing in Torquay, when the mistress is in Scotland?’

‘Visiting his original family,’ said Robin, wishing she could see Strike’s face as she delivered the next bit of news. ‘He’s a bigamist.’

Her announcement was greeted with total silence.”

Robin had pretended to be conducting a survey to get information on Tufty, or Edward John Campion, when a helpful neighbor told her all she knew about Tufty and his first family. 

^{Troubled Blood, Chapter 3}