Brian, the following information may help:-

1851 Liverpool, 59 Frederick Street.

Mary Kneen 49 Widow Provisions Dealer, Workington
Thomas 24 Optician, Liverpool, (recorded twice.)
Ellen 26
John 20
James 19
Jane 17
William 13
Mary 10
Joseph 6
Ellen Potter 70 aunt, Workington

There is a death for a Thomas Kneen 1849 in Free BMD.

Taking Mary is 49 there is an IGI entry for a Thomas Kneen 1801 in Liverpool the son of Thomas Kneen and Eleanor Hilditch. They were married in Liverpool 1786 using the name Hilldage.

Can any of this be related to your records for the manx connection?

Len Faragher