Hi: I've been to Lichfield, and there is bad news

Coverage of BT's for Brimington is - baptisms 1800-1805 and then 1813 onwards, and the same for burials. The 1800-1805 records are on two separate sheets of parchment. 1813 onwards are the printed pages.
The only instance of the Allen surname was a burial - 31 August 1803, Margaret, daughter of Robert and Jane Allen.
The next instance of the Allen surname is the baptism of Sabra, daughter of Joseph (a Collier) and Mary Allen of Brimington - 25 September 1814. And this baptism is available to view via Ancestry.
Very sorry
