I recently found the following link which claims to offer downloads of Haynes manuals for the 407 (there is a fee).
Unfortunately none of the after market publishers have produced a workshop manual for this vehicle.
They suggested I seek the Peugeot workshop manual. Is this available and what does it cost?
I have found workshop manuals good value even though they tend to be expensive - I have one for my 1989 Ford F150 and it has paid for itself many times over. But one of the sad trends with modern vehicles is that they do not seem as accessible to DIY, as the thread about removing the 407 console illustrates. Add engine management systems and 'drive by wire' multiplexing and the days when you understood fully what was going on under the bonnet recede further into the past.