Chatsworth?
 

Disappointing grey coupled with a bad camera I’d say, I’ll check the Reg later Ian.

OK mate although the seller calls it brown.

This vehicle was the 15,475th ZT to run off the production line, out of 18,894
This vehicle was the 2,854th ZT CDTi + (135) to be made out of 4,184
This vehicle was the 2,404th ZT in XPower Grey (code: LEF) to be made out of 3,143 XPower Grey ZTs

X Power grey/Tempest (LEF).
Got two of them - the full O/S oblique shot has got some flare in the top LH corner so I'd say the sun makes it 'look' brownish but the seller can't know what he's talking about (or he's seriously colour blind).

Only 11 ZTs originally produced in "Chatsworth", so it was always unlikely. I have one of them, and it has never looked brown, although the V5 does say bronze. When it shades in different lights, it tends to look green - well, in my eyes anyway!

Chatsworth was part of the Monogram options.
Cost an extra £1000 at the time.
It is a Supertallic paint.
Colour code IAE
Full correct name is Elegant Bronze.
DVLA won't have an option for that so closest would be " Bronze"
Same as Tempest Grey/ X Power grey ( same thing ) it will just say "Grey" on the log book.
So does my Missus Focus ST. That says Grey. Now't like Tempest but ""Grey.""
My ZTT just says "Red". Only DVLA option.

Forgot to add....Whatever you do don't scratch it !
Impossible to just touch up and the paint for a panel re-spray will cost an arm and a leg

So, back to the OP's post, it "could" be a Monogram car. Those paints are almost impossible to photograph and get it to show correct.