Hi Howard
I am sorry but I can't help with your Joseph Timberlake as my burials don't go much past 1850.
Not sure if these will help you much either as there isn't a lot of detail with them but here goes.
Burials at Sarratt Holy Cross
There are 2 Elizabeth's, unfortunately no ages given, one buried 24 Jan 1805 & the other 26 April 1805.
Mathew 28 April 1803 again no age given.
I do have the MI's for Sarratt Holy Cross & these burials aren't mentioned so presumably the graves have dissappeared.
Kings Langley All Saints
Elizabeth 22 Dec 1816 aged 3months.
Jane 22 Feb 1825 aged 18months, abode Langley Hill.
Jane 17 Nov 1841 aged 84.
Chipperfield Saint Pauls.
Mathew 14 June 1846 aged 60.
Only James Timberlake's are Bushey & Watford.
Hope there's something there to help you although there a quite a lot of other Timberlakes in K/L.
Thank you very much for your offer of help, although my lot are mainly Herts & Bucks I haven't yet come across any Timberlakes.

Regards
Maddie