2012 1.6 titanium petrol focus mk3 

Replaced both H7 bulbs, however the left hand headlight H7 bulb including all the other bulbs H1,W5W etc within the headlight remain permanently on but at reduced power they remain on but dim

When using the headlight flasher the indicator flashes instead of the H1 bulb!

In some instances the left hand light doesn't work at all

Right hand headlight no issues whatsoever

Any ideas what would cause this?

 

Sounds a bit like earthing issue, when earth/return fails , the power will usually try to return through another bulb and the lowest lamp lights . I would first check the return cable from the headlamp asy 

As Roger has said, it is an earth fault. The main negative lead to the headlight assembly has broken. The wire may have corroded or the ground point become very rusty and the terminal is making a very poor contact with the chassis.

Will have a look, any ideas where the ground is located for the left headlight?

Looked at the connector and removed some of the wiring from the loom, couldn't remove much as the loom splits into other areas

Nothing untoward found but noticed some of the terminals on the connector block and on the headlight terminals dirty with green residue. Cleaned as best as I could, so far the headlights are working as expected but time will tell...

 

3 hours ago, ash29109 said:

noticed some of the terminals on the connector block and on the headlight terminals dirty with green residue.

That is the copper contacts corroding. Spray with WD40 to prevent further damage.