A Home Affairs department paper later points out that flooding Essex to protect London "seems unlikely to prove practicable".
Large sections of defences would have to be destroyed "which together have cost £250 million".
Explosive charges would have to be laid in advance but there were doubts about when exactly to trigger them.
It was noted:
The last measurement of tidal surge is at Southend, approximately an hour before it would reach central London, but the height of the eventual tidal wave in central London could not be predicted with complete accuracy, and thus the defences could well be blown up unnecessarily.
There is a major political difficulty in that the Government would have to take responsibility for deliberately flooding Kent and Essex in order to protect central London.
It seems doubtful therefore whether the breaching of the downstream walls should be contemplated. If the committee decided that the possibility was worth considering, it would need not only very thorough investigation but also most sensitive handling because of the alarm which might be created in Canvey Island and elsewhere"
More top news
The actor Hugh Grant has praised a man from Leiston who's launched a Facebook campaign against dog owners who don't clean up their mess
RAF Tornados will continue to carry out air strikes against so-called Islamic State into 2017, the Defence Secretary has announced.
A man from Huntingdon has been jailed for inflicting life threatening injuries on his friend after a trivial argument