Thanks for everyone's help on this, i really appreciate it. I found Grace's death, of all things, in 1846 which is why I couldn't find her. The 1851 census was a red herring because her husband had put initials only and it was him that had married again (then dying 2 years after) when id thought she had. What a sad story! So much TB!
All your help with the siblings was great though because it led me to a farmhouse actually called Tadlow (after the Tadloos) in Uxbridge who rented the house for decades. It's still there and lovely to find an existing connection.