Morning Don
Not sure if this helps, did a little scanning of the Taranto Raid book by David Wragg and found the following.
For the Taranto raid, those swordfish assigned to torpedo-bombing sorties would have to carry 60 gallon long range tanks, which would be fitted by means of metal straps into the observers's middle cockpit on each torpedo carrying aircraft: he in turn would displace the TAG in the cramped rear cockpit. The bomber swordfish would also have a extra tank, but fitted under the fuselage. Apart from pushing the observer into the rear cockpit, the other disadvantage of having the long range fuel tank in the middle cockpit was that there was a real danger of fuel being vented into the rear cockpit, leaving the observer up to his waist in highly inflammable and explosive high octane petrol.
Hope this helps.
All the best
Paul