retrieves incorrect data for WALTON ON THAMES

Query->
80 kings road
walton
KT12 2RD

Returns ->
SAON:
PAON: 80
Street: Kings Road
Locality:
Town: Walton On Thames <<<<<<<<<<<<<<<
Postcode: KT12 2RD

However.....
Query->
80 kings road
walton on thames
KT12 2RD

Returns ->
SAON:
PAON: 80
Street: Kings Road
Locality:
Town: LONDON <<<<<<<<<<<<<<<<<<<
Postcode: KT12 2RD

Any known reason for this behaviour?
Thanks!