Hello jomiskelly,
I have done a street search of Llandudno in the 1851 census. There is no sign of Thomas Williams that I could see.
One entry that did strike me was the following:
Llandudno, HO107/2519 Page 27. Pen y Fron number 3
John Williams head, widower, aged 43, assistant overseer to farmer, born Llanelian.
Mary Williams, daug, aged 12, born Llandudno.
Jane Williams, daug, aged 10, born Llandudno.
Ann Griffiths, aged 24, servant, born Denb, Llandrillo.
I am fairly sure that Pen y Fron is on the lower slopes of the Great Orme.
I am not sure of this but it is worth bearing in mind. The place of birth is the problem.
Re the grave(s) those in St Tudno's in the old cemetery are few now and most are illegible. I gave up looking for my ancestors who are buried there. Best to get the details. sttudnos(at)llandudno-parish.org.uk
St Tudno's has a very good website if you haven't seen it
http://www.llandudno-parish.org.uk/sttudno.htmlJo