Care services minister Paul Burstow announced the figure last month.
After an initial request for details was rejected, GP asked for documents explaining the evidence using Freedom of Information rules.
The DH said revealing the evidence could ‘inhibit future policy delivery' and ‘undermine ministers’ and officials’ space for consideration and debate’.
Below is the request by GP, and the DH's full response.
GP has requested an internal review of its decision, and will report the outcome when available.