Allen becomes the third to join JG from Specialist Leisure Group (SLG) in less than a month.
Shearings parent SLG collapsed in May, with JG acquiring the National brand in July.
JG has since appointed former Shearings trade sales manager Claire Dutton to a like role at JG, and Julie Wilson as groups manager.
Allen will focus on short breaks, sports breaks, family and tribute product development and delivery.
