Hi Janet,
were you aware you can search the forum for previous related threads ?
There are several prior threads re William Wickenden(s?)which may be of interest:

http://www.forum.forest-of-dean.net/index.php?id=31131
http://www.forum.forest-of-dean.net/index.php?id=4214

I see MPG aka Marilyn Griffiths, one of this site's hardest working contributors, is a descendant of William so may be able to help you.
http://www.forum.forest-of-dean.net/index.php?id=25720
and
http://www.forum.forest-of-dean.net/index.php?id=4214
Follow this thread to also find Alice Wickenden.

Unfortunately FreeBMD only covers the years after 1837, so perhaps no help, but there are some TW Burials within Glos, Glamorgan & Monmouthshire with the earliest being:

Surname Given Name Age District Volume Page Transcriber
Deaths Mar 1838
Webster Thomas Merthyr Tydfil XXVI __1 AnneM

Surname Given Name Age District Volume Page Transcriber
Deaths Mar 1844
WEBSTER Thomas Abergavenny 26 3 kayoung

Surname Given Name Age District Volume Page Transcriber
Deaths Mar 1850
WEBSTER Thomas Ross 26 197 mikec

So (to my surprise at least) not as rare a name as I hoped..

Good luck!