Dennis F12 Pump Escape 

And just how useful would the hook ladders be in a world of sealed unit double glazing?

@@neiloflongbeck5705 there are still a number actually large number of properties where hook ladders could still be essential..esp maids vale. and st Johns wood..

And they also should have never discontinued using the escape ladder

They have decomissioned it due to health and saftey gone through the roof