Hi Nirvana
I took a look at the Census to get a "feel"....
1841: Devons Le West, Bromley St Leonards. Middlesex
John SMITH 56 - Brick Layer
Mary 40
John 30
George 25 J Brick L.
Willm 18 J Brick L.
James 5
Henry 4
Sarah 3
Joseph 2
Mary Ann 1
Caroline YORK 15, F.S.
ALL Born Middlesex
1851: Devons Lane, Bromley St Leonards
Head: John SMITH 66, Master Bricklayer employing 8 men, b Ashen? Essex
Wife: Elizabeth 50, b Heaverhill Essex
Son: William 27
Son: James 15,
Dau: Sarah 12,
Son: Henry 13,
Son: Joseph 10,
Dau: Mary Ann 9
Son: William 7
Lodger: Mary Ann THOMPSON 71, Wid, Retired Publican, b Nibley Glouc.
All children Born Middlesex
Did you note - there are two sons in the household named William ? That might suggest 1 of them was not William's natural child but came to the marriage with a new wife?? Or it might be that William the younger is actually a Grandson....
Also the lodger, she may very well be a relative......have you already tried to follow her up?
1861: 4 Crown ----------?, Bromley St Leonards, Middlesex
Head: Henry SMITH 22??, Bricklayers Labourer, b Bromley Middlesex
Wife: Emma SMITH 22, b Plaistow Essex
Son: Walter Thomas?? SMITH 2 months, b Bromley
This Census page is poor quality and hard to read in places - plus there is an enumerator's check mark thru the first digit in Henry's age - it is cetainley something-2 - could be 22 (look at how the 2 in the baby's age is written) but it could be 32 or 42, and as you say perhaps 42 is a transpostion of "24"
Now here's the luck......
Immediately above Henry and Emma on that 1861, same page AND at the same address is a seperate headed family....
Head: Thomas REID 65, Retired Seaman, b Plaistow Essex
Wife: Sarah 55, -------? Hants
Dau: Alice 24, unm, -------------- -------------?, b Plaistow Essex
(Can't read Alice's occupation!. I think the surname is spelled REID - but it could be REED)
Cheers
AMBLY