Yes. And of Essex if it were the MBW.

I was ignoring Essex as it didn't seem to have any representation on the
metropolitan board
(http://en.wikipedia.org/wiki/Metropo...ment_Act_1855), and also had
the same arms as Middlesex.

I'm pretty sure that 1 o'clock is Guildford (the county town of Surrey).
I've not found details of them as they were when the bridge was
commissioned but the former Borough Council's arms were very similar and
incorporated a castle with 3 towers between 2 woolpacks. See
http://www.civicheraldry.co.uk/surrey_ob.html

5 o'clock seems similarly to be the county town of Essex - Colchester. See
http://www.civicheraldry.co.uk/east_anglia_essex.html

They seem as good as suggestions as any we are likely to get!

G.