I was an altar-boy at St. John's R.C. in the 1950's there was a story passed on from one generation of altar boys to the next that a tunnel existed running from under the high altar of St. John's to HAIGH HALL!
Certainly there was a set of steps behind the high altar, out of view of the
congregation, that descended to where we knew not (and were definitely discouraged from finding out by the Parish Priest). At the main Mass on Sundays there were usually about eight altar boys (it was a kind of three-line whip) and we sat on benches to the side of the altar. Obviously those at the inner ends of the two benches could not be seen by the congregation and a fair amount of malarkey went on during the sermon
but, respect for authority being what it was in those days, I cannot recall anyone ever daring to go against the PP's express command that we were not to go down the steps.
I expect that it was probably just a boring old cellar! The church building dates from about 1820 I believe.