Bit too far east unless it wasn't leaving a trail. Couple of airliners just went over eastbound leaving very short trails. Should be able to see them over Southend, but cloud/neighbouring houses provide too much clutter!
Saw a French A320 and a Thy B777 have a mid air last night... 1000' vertically between them but from where I was standing the old adage "frequency separation if nothing else" rose to mind!