Boulton Paul Defiant, single-seat fighter in the BoB ?

That could make sense if you take into account that there was a huge shortage of nightfighters and that was the combat role the BP Defiant ended up quite successfully filling, an extra single seater at that point would be no real benefit.

 

Was the Defiant successful? The only account I've read implied they spent most of their time blundering around trying to figure out where they were and where they were going to land.

 

I believe the Defiant was the most successful of the early nightfighters of WWII.

It was certainly not a failure. 152 enemy aircraft shot down for the loss of 37 Defiants. That includes 28 Bf 109s and 28 Ju 88s. Almost all Defiants lost in combat were shot down by Bf 109s, only one was lost to return fire from a bomber.

 

Well, they had the higest interception/kill ratio of any WW2 nightfighter.

But how many intercepts they made is another matter...
Bear in mind that at this point, nightfighters were guided by ground-based radar, so a 2-seater was infinately preferrable to a single-seat (2 pairs of eyes are better than 1)

 

A bit on the side of the topic, but an interesting fact nonetheless :

The top-scoring Defiant crew, R. Thorn and F. Barker, had no less than 13 kills on their tally, only one of them a night kill. That should put Barker amongst the highest scoring air gunners of all time as well.