Hi John
thanks for your help, If William hadn't been born in Ripley there would be several possibilities for him, I've got the link for the Hampsthwaite registers and checked with the Hampsthwaite parish records in Harrogate Library but it does have him down as born Ripley, the possibility that he might have lived in Ripley and not been born there had crossed my mind.
There are other Malthouse families around at the same time as Ambrose, with such an unusual name it seems sad that he doesn't appear to be in the registers but this has happened with many of mine and Pete's ancestors and unfortunately makes it much harder to track them down.
Julie