Looking for protype LNER Teak info

Greetings,

I am looking to get some protoype information for building my live steam Mallard rake.  Granted, it is OO, though being live steam, I think it qualifies for MLS.  Especially considering it will be running on an elevated track in the backyard  /DesktopModules/NTForums/themes/mls/emoticons/tongue.gif

The first question I have is...  What is the purpose of a brake car?  How many would have been on an 8-9 car rake behind the Mallard running the teak cars between King's Cross and Grantham back in the day?  Here in the states, I've never encountered this during my research of US prototypes, so I'm baffled.

I have been gathering Hornby teak coaches from across the world, and I'm pleased to say I have 10 teak cars, and an old Pullman "Pheonix" Parlour car.  Some are here, and the last ones are in transit.  Without having them in hand and checking for sure, I think they are as follows:

2 full coaches
2 sleepers
1 oval ended window coach
1 Pullman "Pheonix" Parlour (not teak)
5 coach/brakes, hard to tell for sure from the photos.

Would the cars have diaphrams between them?  What would a prototypical rake look like from beginning to end, and how many brake coaches would be in an average train at most?

Also, any web sites than folks can offer for research would be most appreciated.  Seeing as I've recently settled in for a 16 hour shift (and it is dead out there tonight), I'm sure I'll find some info in the next few hours.

Thank you,

Kent