Rees, Thomas & John Thomas. Hanes Eglwysi Annibynnol Cymru (History of the Welsh Independent Churches), 4 volumes (published 1871+). Here is the entry from this book for Llanbedrog chapel (in Welsh ) - with translation
Church and chapel data from The Religious census of 1851 : A Calendar of the returns relating to Wales, Vol 11, North Wales. Ed. by Ieuan Gwynedd Jones, UWP,1981. The names given towards the end of each entry are those of the informants.
Llanbedrog Parish; Statistics; Area 2548 acres; Population 245 males, 280 females, total 525
Llanbedrog Parish Church Attendance - usual - 60 Services in Welsh Informant; John Owen, Rector
Page from Llanbedrog Parish Register of Baptisms 1813-1821 - on the People's Collection Wales site
" ..... contains a memorandum of the population in the parish on June 1811 and a survey of the population made on 28 May 1821. The population of the parish increased from 393 in 1811 to 440 in 1821...."