According to a member submission on the IGI, which doesn't show as an extracted item, John Arch who was buried in Cardington was baptised in Cardington on 20 Aug 1843, the son of John Arch and Martha Sims. It needs checking with the parish register to see if it's real, but it might explain the tree that Trish found.
However, if John Arch really was the father of all the children, and he was the only John Arch in Beds at that time, he seems to have flitted between two ladies:
John 1843 mother Martha
John Jackson 1848
Martha Sims 1851 mother Martha
John Sims 1855 mother Martha