Hi Ken,
Here's a list of what I have for William & Mary. All of these are attributed to "William & Mary" and Christened in the Catherdal (Manchester), although the dates for some appear to overlap. These are all Christening dates.
Ann Lawton - 20 Feb 1791
Mary Lawton - 28 Sep 1792
Charles Lawton - 17 Mar 1793 (1841 Census - Bricklayer. Living in Kirby Street, Ancoats, Manchester. On this census, there is a June Lawton (aged 35) living with the family - she is possibly a sister or a sister-in-law. I will not add her to the tree until I can verify her position.
1851 Census - Master Bricklayer. Living at 35 Dixon Street, St Jude's, Ancoats, Manchester.
1861 Census - Living in Dearden Street, Hulme, Manchester, England. Employed as a Bricklayer)
John Lawton - 14 Apr 1793
James Lawton - 27 Sep 1795 (James married Eliza and two of their children had the middle name of "Brough" - this ties in with Sampson's child, Eliza, having the middle name of "Browf" - must have had strong accents

)
Mary Lawton - 5 Jun 1796
William Lawton - 28 Jan 1798 (William married Hannah Quinn and there are more ties with this family and the Lawtons showing up on the 1841 census. 1841 Census - Bricklayer. Living in Spinner Street, Ancoats, Manchester. Also on this page are James & Eliza with their family.)
Sampson Lawton - 16 Jun 1799 (Sampson was a bricklayer - he went on to buy a shop in Wharf Street)
Sarah Lawton - 5 Jul 1801
Thomas Lawton - 6 Jun 1802 (You have more details than me on Thomas)
John Lawton - 14 Oct 1804 (1841 census has a John Lawton & family living in Manchester. I am pretty sure that he is connected to Sampson and is probably his brother. Indicators for this are that he too is a bricklayer and that he has a son named Sampson. DOB, on the census, is given as abt 1811 (can be as much as 5 years out). The DOB of their son, William, would mean that John was only 15 when his son was born. I am therefore adding this family group to the tree until I can prove otherwise.
I cannot find any children of John & Margaret prior to Sampson. There was a marriage of John Lawton to Margaret Quin in the Cathedral, Manchester on 23 APR 1835. This also ties in with the other Lawton/Quinn relationships.)