From ESC 21 July 2011
In the opinion of the Electrical Safety Council, there is no "significant risk" to children from 13 Amp socket-outlets fully conforming to the product standard BS 1363. Having integral safety shutters, they are widely judged to be of the safest design currently installed in Europe, and the Electrical Safety Council is not aware of any incident data to suggest that there is any real or potential problem with this type of socket-outlet.
This position has also been taken by the BSI technical committee responsible for BS 1363.
It is arguable that fitting a blanking plug into a socket-outlet will reduce the risk of electric shock to a child even further, since it will make access to electricity even more difficult. Whether it is justifiable to require their use in certain environments is less clear.
There is always some risk of electric shock with any electrical equipment and the decision on how much risk is acceptable is ultimately subjective. Absolute safety can be achieved only by the permanent removal of the electricity supply.
Babies and toddlers are inherently risk-prone and should never be left unattended and allowed to 'play' with socket-outlets. Eternal vigilance is the only reliable safeguard in this respect, as is the case with any other potential (and frequently much greater) hazard that they might encounter.