Brake lines - MOT fail :-(

[Smegmium]

Morning all!

Just had my '05 LWB connect fail its MOT on corroded front-to-back brake line(s?)

I haven't had a chance to get under the van yet so thought i'd ask, is there one or two of them? and how are they (it) routed?

Apart from the inevitable seized unions and brake fluid drain/re-bleed, how much of a job are they to change?