Most H4 headlamp bulbs are held into the lens with a spring clip.

Once upon a time, many years ago replacing these bulbs was easy as you could have easy access to the bulb, tge bulb holder and retaining clip.

On the XJS you can't see the rear of the lamp and the spring retaining clip is detachable (unhelpful).
If anyone has a good photo of the rear of the headlamp that shows the spring fitting it would be helpful.

 

Paul
I do not have a photo. But the basically V shaped clip first fits onto the headlight unit with the open ends of the V free. The H4 can only fit into the headlight one way. Then the clip come down to trap the H4 and you pinch in the free ends inwards to spring them into the slots on the opposite side of the headlight unit.

 

Maybe this will assist a tad.

 

This is where the BULB ACCESS PANEL in your wheel fender well comes into play...

 

Thanks to all for taking the time to reply.
I have changed headlamp bulbs on my XJS before,without problem, this time however the closed end of the V as Greg describes it has become detached from the lamp and i am unsure if it locates in a clip .

if i can reattach the closed end then i am ok with the getting the two open ends to lock in place.

the headlamp access plate in wheelarch doesn't allow for good visibility.

I am considering removing the lamp assembly (1993 model single headlamp)

 

Ooooooh.

Memory, and only 4 coffees so far.

That closed end is simply held by a section of the ring the bulb sits in and folded over to form the hinge. Rather crude, but is works.

Lamp out is the best way.

 

Thanks Grant great advice