Having had a successful day at Hertford R.O. examining the parish records of Sarratt, I can now update my original post.
Richard Timberlake, born Sarrett 1756 (wife Jane Weedon)was the son of Matthew(1) Timberlake and Elizabeth. They had three other children, Ann (bap 1752), Alice (bap 1754) and Thomas (bap 1770).
Matthew(1) (bap 1726)was the eldest son of Matthew(2) and Mary (not Jane as the IGI suggests). Other children of this couple were: Thomas (bap 1730, died 1731), Mary (bap 1732), William (bap 1736), Elizabeth (bap 1740), Susannah (bap 1758) and James (bap 1760).
Matthew(2) (bap 1704)was the ninth child of John Timberlake and Marie Lewin. The other children were John (bap 1685, died 1685 - this one is erroneously recorded on the IGI as the father of Matthew(2)). Maria (bap 1687), William (bap 1688, died 1688), John (bap 1690), Alice (bap 1692), William (bap 1694), Daniel (bap 1698), Thomas (bap 1698), Susannah (bap 1704), Elizabeth (bap 1709), and Mary (bap 1716).
John Timberlake was born in Chenies (according to the wedding details). Chenies is in Buckinghamshire - which means a trip to the record office at Aylesbury to see if I can find out more details.