Good Morning Simon, 
 
Thanks for your question. 
 
The spring unit does have a wire metal frame to it to add extra support. This is on both sides of the mattress as all mattresses within this range are fully turnable. 
 
All mattresses within the Artisan range including the Bespoke 002 have a depth of 11-12". Due to the natural fillings this accounts for the slight difference.
 

 
The Artisan Base, that we pair with our Artisan mattresses as standard, are 12" in depth with 2" for castors without drawers. Alternatively, if you add drawers it adds an additional inch taking the total to 15". 
 
We can supply a non-standard East to West split on the base for an additional charge of 10% but please note that there is no standard 60 day love it or return it guarantee on products like this as we have limited resale ability on them. 
 
We can't unfortunately supply a large foot end drawer; Our drawers options are 2 Full Side Drawers, 4 Full Side Drawers or 4 Drawers, 2 Half. 
 
We pair our Artisan mattresses with our Artisan (Pocket Sprung or Bonnel Coil) Base as standard but it can be used with any base. A Pocket Sprung Base will give the mattress a slightly softer feel whereas a solid platform top base will give the mattress a slightly firmer feel. 
 
I hope this has answered your questions fully but if you do have any further queries please don't hesitate to contact our office on 0161 437 4419. Our office is open Monday to Friday 8am to 8pm and Saturday and Sunday 10am to 4pm. 
 
Kind Regards, Lee.