had a look at Johnathan Dumbell's will in museum today - little relevance to you as main will dated 1815 with a codicil 1826 (both dated from poulton near Warrington) - names wife + money in trust for sons + exors (wife + two friends both dead by probate) - £5000 left to wife.
I didn't get chance to look at Rushen baptismal reg - I suspect this Johnathan is not your John Dumbell, errant father.