Creffield was built on land occupied by the Elms estate and Fordhook House.
The Elms Estate
The Elms estate covered much of the CARA area from Birch Grove eastwards and Creffield Road northwards.
Here’s a summary of the development of the houses on the estate provided by local resident John Woodcock. It includes dates of development, names of builders and building leases.
The Estate Builders in the 19th and 20th Centuries :

Some other snippets of local history about The Elms, Twyford Avenue and Crescent, Hale Gardens, Fordhook Bridge and Bollo Brook (which is now piped underground) are available here (source unknown).
The house and grounds of the Elms (now Twyford School) were bought by J.K Farnell & Co in 1898 who built a factory on site manufacturing teddy bears. It is believed that Daphne Milne (wife of A.A. Milne) purchased a Farnell Alpha Bear in Harrods in 1921 for their son Christopher Robin, which became the inspiration for Winnie the Pooh. The bear now lives at, and is on display at the New York Public Library.

Fordhook House
Fordhook Avenue, Byron Road and the lower section of Wolverton Gardens were built on the old Fordhook estate, which bordered the Elms estate. This history was written by former local resident Rupert Debarr for the street party to mark the centenary of Fordhook and Byron in 2004.
Some other snippets of local history about Fordhook House and former residents are given in this extract (source unknown).