And that baptism also appears on the Buckinghamshire baptisms via FindMyPast. However, parish register appears to indicate 1713, whilst the BT's say 1714. Only transcriptions available.
A brother for Mary - Thomas, baptised 21 October 1715 at Wing.
No sign of Thomas senior, or a marriage for Thomas and Martha.
Added: From the link given by tazzie - The baptism for Thomas junior states that he is the son of Thomas Lock of Ascot.