It was a KLM flight, KLM flight number (KLM1338), KLM colour scheme,
The above is correct but....
With a cityhopper colour scheme - the aircraft is a VLM F50 that has a VLM crew who operate "on behalf of KLM"
Go here and then select find flight and search for LHR/RTM - on KL1338 click the F50 link