The pilots may have been trouble shooting a problem or waiting for instructions from the company.
Either way it was probably necessary they stayed close to the Airport if there had been no reason they would have been on their way and not wasting fuel!
I used to live adjacent to the Airport in Norwich and enjoyed the comings and goings, nothing like listening to a jet engine at take off thrust it never got annoying for me, even the Helicopters coming and going you get used to.
Screaming kids and barking dogs however drive me insane!