I think you`ve the right marriage for William Arliss and Frances Pawson.
FreeReg has a baptism for William Arliss on the 8th July 1784 at St James Church Louth, making him about 22 at the time.
I couldn`t find a baptism for Frances, although there are a few Pawsons in Louth at that time.
I checked the baptisms for any others between Harriet in 1811 and the 1829. There are lot of Arlisses but none with William and Frances as parents.
Then I`ve looked for any burials, to see if they had any infant deaths; this was the result.
Mary Arliss dau of Frances Arliss on 3rd Nov 1808 "a base child" ? St James
Jane dau of William Arliss on 5th Dec 1811 ? "
Peter age 7 on 7th Aug 1815 "
It doesn`t equate with the Anc find!
Then there`s this baptism, Sarah on the 10th April 1833 mother Harriet Arliss singlewoman.