in the United Kingdom. The Thames flows through or alongside Ashton Keynes , Cricklade , Lechlade , Oxford , Abingdon , Wallingford , Goring-on-Thames , Reading , Henley-on-Thames , Marlow , Maidenhead , Windsor , Eton , Staines-upon-Thames , Sunbury , Weybridge , Walton-on-Thames and Thames Ditton before entering the Greater