The "shack" is 60 today and although it looks to me like a shed on wheels it is still a beast of a machine:

It was developed by Avro from the Avro Lincoln bomber with a new fuselage and the type is named after the polar explorer Sir Ernest Shackleton.

I have found some great information regarding the Shackleton:

• First view of the Shackleton from our archives 
• Images of the "Shack" from AirSpace and WikiCommons
• The South African museum has some great images of the Shackleton

Here's a YouTube clip of the beast in action: