I've made a mistake somewhere

[Josef]

Yeah so as we thought your starter motor has an in-built solenoid. The white/red wire to the terminal on the ignition switch that is live when you turn the key against its spring to start the car is of the correct colour (and you should be able to see it on your wiring diagram). The ignition light on the dash in effect tells you if the Dynamo/alternator is charging or not. It should light when you turn the key to first position, and then extinguish when the engine starts. 

[DanMi]

yes the starter motor is a replacement probably far more modern and will spin the engine faster, though mine always starts with Ok not the original starter but a recon from 1994, It has a solenoid built in unlike the original. The white red is the starter activator wire from the ignition switch which would normally go to the solenoid on the bulkhead but has clearly been extended. If there is only 1 in-line fuse no harm using it for both flasher and horn they are neither a constant use item. Originality does not seem to have been a concern of the PO.  have you found the purple/yellow to the horns and the purple/black to the horn push or were those improvised. To be honest if you don't want originality than modern relays are fine.

wiring the horn is pretty simple. Run a wire from the fuse to both +ves on the relay, a wire to the purple/black of the horn push from the -ve low tension terminal and then to earth and a wire from the relay load to the horns. If you intend to use the horn push pay attention to the earth, you may need to put a wire across the column UJ and another from the steering rack grease point to the chassis The original relay only used 3 connectors as the 2 +ves are connected within.

It appears that the PO has altered the brake lights as well. This originally would have been a switch on the brake pedal but it looks like they have used a 3 way hydraulic connector where the starter solenoid should be with a hydraulic switch. This is just far more complicated than original for no actual benefit and also potentially and extra leak point in the brakes so WHY? (rhetorical)

If it was my car I would put it pretty much back to factory spec, retaining the alternator ( I would use original wiring with a dummy control box to join the brown wires) I would also use an original starter solenoid with the newer starter, yes that would mean a solenoid (basically a big relay) firing another solenoid. Plus I would alter the brakes to use the pedal switch, but then I quite like things to look original and be easy to return to factory spec even if modified, if later desired. But it is your car so if you want to get what you have working that is good too

[Neil Clark]

I could use a horn switch instead on the dashboard - that would be possible.  Thank you both for the notes and I'll keep posting as things move on.  I think it's a professionally made loom and if I can through to Autospark on the phone I'll ask if they have a wiring colours diagram.    During this forum discussion above I read that they will make the loom with mods for alternators etc etc so that may help.

Re originality I had hoped to get there when I first bought it but now it's not realistic and I'm not a good enough engineer / restorer to get there at sensible money.  It's the original radiator, engine, gearbox, dashboard, boot lid and rear lights but that's about all I can put my hand on my heart about really.  If I can make it a decent car fairly representative of the early engineering, styling and design I'll feel satisfied.  This Spitfire has so many replacement panels and of course a Mk3 chassis with the elephant in the room being these weird wiring extensions.  In the rebuild I found that it's also got the much later rear suspension - and those bling chrome wires about which I am still unsure.  

I've got a 1966 MGB GT which I had professionally restored.  It's very original and I keep it that way.  In the MG world there are an enormous number of "early" cars that we have found are simply a V5 and under bonnet label on a totally unrelated car.  One roadster sold last month via one of the reputable auction houses for a lot of money - but with an MGB GT V5 - it was just a bunch of bits, albeit good new bits and a totally new shell, but nothing to do with being an early MGB.  We pointed it out to the auction house, they just shrugged.

[DanMi]

No 58 year old car is completely original, mine also has the later swing spring a mk4 OD gearbox and many new panels, but they are as original or easy to put back if required. The chassis is exactly the same now that it has the early bonnet mounts. I've also swapped the indicators and headlight stalks to be on the same side as a modern and wired as the later cars with a 2 position column switch, but all easily reversed if desired.

[DanMi]

Oh and I have a set of wire wheels rotting in the garden, they look fantastic, but you can feel them flex when cornering and whatever I did there was always some play in the hub splines . Plus you have inner tubes almost certainly with tyres not designed for them. It now has 4.5J standard wheels from a Vitesse, but they where an optional extra at the time

[Neil Clark]

Hopefully we can exchange notes with the cars side by side one day!

[Josef]

For me Neil the fact that you’ve saved something that could realistically have been written off fully and destroyed is the important thing. There’s not many early Spitfires left (though the number is not as small as many eBay sellers like to think!) so keeping one alive is very much a good thing! Any changes are part of its own history / story now anyway, most important is you being happy with how it turns out in the end. 

[Neil Clark]

Thanks Josef.  Today I made major progress on all fronts until I discovered while at Moss that the MotaLita steering wheel and boss that I spent days restoring is so old that the horn push parts and contacts would have to be custom made unless I can find them.  So I'm compromising and have ordered a "momentary" horn switch from Car Builder Solutions as a temporary solution to having a legal horn.  And I've re-done the bullets and spiral wrapped the wiring to the headlights and re-affixed the dashboard now that the wiring behind it is as good as it can be for now.

Tonight, joy of joys, I refitted the front number plate.  Perhaps tomorrow or Wednesday I can take her off SORN and start taxiing trials on the local roads!

[DanMi]

• that looks absolutely identical to my moto lita. The mota lita horn push won't fit but the standard Triumph one will with the origianl horn pencil the standard horn pencil. The only issue I can see is that the nut is too thick and why oh why has someone punched it! Plus it really looks period

[Neil Clark]

We tried it Dan.  It's just different somehow.  When I got the car the Triumph horn push it had looked quite different to yours.  The TR6 one from Moss would fit if I filed off one part but for the money and risk I passed for today.  The one it came with originally has disappeared somewhere along the road to restoration and since I can find everything else and account for what I junked it's probably hiding - but I've unpacked and repacked every crate of parts over the last few days.  I've got the spring pencil but that's it.

[DanMi]

might be worth having a chat with mota-lita as the boss is still available today https://www.moto-lita.co.uk/bosses/b20-sc/, though mine is period and the horn push taken straight from the original 16 inch wheel without the 3 pronged thingy. They don't supply the push though

[Neil Clark]

Will do Dan thanks, and see where I stand with them.  I'm going to spend a little time to settle it down mechanically once the temporary horn button works.

[Neil Clark]

On the road!  I've put a video under the restoration forum.