This is the prototype Bristol Type 167, <a href="https://en.wikipedia.org/wiki/Bristol_Brabazon" class="extiw" title="w:Bristol Brabazon">Brabazon</a>, which made its first flight on 4 September 1949.
British official photographer
1950-02
<a rel="nofollow" class="external text" href="http://www.iwmcollections.org.uk/qryImages.php">www.iwmcollections.org.uk</a> Catalogue Number: ATP 18936G