Yeah I'm aware it's for a higher wattage than I have. I couldn't find any lower than that really. I remember you recommended a 72 to me as working in a pinch (but that didn't ship to my location so it didn't work) so I figured the next best would be to find the closest to the original value that I can and the SX70 was what I could get. I hope since it's only the ignitor that runs for a small amount of time that it won't matter too much

As long as it doesn't immediately explode I'll be fine with it

Unfortunately the numbering system doesn't always make sense, or bear any resemblance to the rating the ignitor is for. The SX26 is self-explanatory, but the SX72 is rated for a 35W lamp at a supply voltage of 240V, what supply voltage do you have there..?

Still looking here, not found anything yet but there is a listing on UK eBay for an SX72, see here, he says he will only ship to the UK so if necessary I can get it and forward it on.

Yep. I'm aware they're not close. But I wasn't going off of the numbering in the naming. I was going off datasheet. See screenshots in previous post. It's 1.0KV Vs 1.2KV and the other specs all seem the same. I could be wrong on that though

Well, both have 198V trigger point, so the biggest compatibility problem for parallel ignitors isn't there (like it is between st2 vs st10 fluorescent starters). The higher open circuit amplitude voltage (so how high is the igniter capable to go) just gives more margin to ignite the lamp, but (contrary to what many wrongly believe) there is no problem for the lamp at all - the lamp will always dictate what voltage would be there, if that is below what the igniter is capable of.
So I wouldn't think your combination would cause any troubless.
And yes, the wiring you have shown is correct, the capacitor is indeed just for the mains side power factor correction.
Hope you did succeed to make the ignitor working...

Ahhhh awesome that is good to hear. Thank you for the reply. And just so I can clarify it in my head do I need the cap for it to run or will it just make it run better? Because I know in some cases PFC is very important to electronics functioning like in inductive motors. But is it required in this case or will it just improve efficiency? Because if it's a nonessential role I might well leave it out for now and just go with it as is until I can get a cap from somewhere. Also if needed what capacitance should I get?

The capacitor is across the mains input, so it's purely for power factor correction. It's not essential, although the perfectionist in me always includes one. The rating for this circuit is 5µF and lo and behold I found one in my box of spares, still not found an ignitor yet but that seller I linked to has several, let me know if you want me to order one for you.

The only thing it does is to reduce the mains input wiring load. So when you have really a lot of fixtures in your installation, improving the power factor from 0.66 to 0.95 means you can handle the installation with less circuit branches (e.g. 6 instead of 10 15A branches in case of 18kW installation). And if you were such a large power drawing business, utilities would most likely bill for the reactive power you draw (as it causes extra losses in the power distribution network but carries no useful power).
With a single 26W fixture at home you don't need to worry about at all, the 0.36A instead of 0.15A makes no difference on your installation, the power draw will be about 30W in either case.

But be aware the capacitor with induction motors is by far not "just for power factor", it is there to provide a phase shift in order to form a rotating field from just a single phase. So there the capacitor is essential part of the motor setup. With larger motors even two capacitors are used: One to keep the motor running efficiently (called "run" capacitor) and a second one connected parallel to the first one to match the motor impedance (so provide the required phase shift) when the motor is starting, hence xalled "motor start". After start, the starting one must be then disconnected. The run capacitor must be of a high quality rype, as it is loaded all the time the motor is running, on the other hand the start capacitor uses to be of some compact (as way higher capacitance is required) type, which will not sustain permanent connection (it will overheat and even without that, its cumulative rated load life uses to be in few 10's of hours range, designed to be connected really just few seconds for each start)

Ahh ok perfect. Thank you. I had a feeling that might be the case but am much more at ease seeing it is definitely the case.
As for the cap on inductance motors I'm aware they need the phase shift for functioning to get the physical alignment right. Honestly I was just using them more as an example I could think of off the top of my head where a PFC is absolutely necessary. Lest you have to manually start the rotation every time. I greatly appreciate the help man

Lest you have to manually start the rotation every time.

Actually many, mainly smaller, induction motors don't use any capacitor at all. Some use "shielded pole" to provide some phase shift for start (smaller fans,...), some use resistive starting winding (most refrigerators).
And some motors even don't use any phase shift at all, they use some other type of motor to spin it up first. Most frequent (mainly for smaller shop machinery in north America where 3 phase power is not that common) are motors which are configured as a repulsion brushed motors for start (feed to the stator winding, brushes are at about 45deg), which are then converted by the starter switch into an actual shorted rotor induction motor (when it spins up, a centrifugal element lifts the brushes from the commutator and let a contact ring short all commutator elements together, forming a shorted rotor induction motor from it for the normal operation). Rest of the world, where practically every customer gets complete 3 phase service, these motors are practically nonexistent (way too complex), using true 3 phase powered motors instead.

Ahhh cheers mate. I greatly appreciate the offer. I first wanna see if my bodge worked. If it did I don't see it necessary to order one. But if it didn't then obviously I'll have to. On that note. Do you have any suggestions of how I could maybe test the ignitor. I was thinking of getting a cheap florescent tube that's also rated at 36W then just hooking it up in circuit as I would the SOX. Then if it properly strikes I'd feel comfortable putting SOX in. Any feedback on this method? would you recommend it or is there something else you'd do?

You don't need to worry using directly the SOX.
There are really just two options: Either it starts normally, or does nothing at all. Nothing else, no tube killing mode nor anything like that. The only variable (when the igniter is marginal or failing) will be the probability when it starts and when does not, so the reliability of the system functioning. But really no risk of any harm to the tube at all (beside the normal wear when it starts). The recommendation to let the tube burn for some hours after it starts applies as well, of course unless something really starts failing catastrophically (like the ignitor smoking or so).

No, I don't think that would work, a fluorescent tube usually starts by what our American friends call the pre-heat method, where the cathode filaments are heated first before the starter switch interrupts the circuit causing an inductive kick. The SOX ignitor (any ignitor really) delivers a high voltage kick to start the lamp in instant 'cold' mode, which might work, but isn't guaranteed and probably won't do the tube any good.

Just connect up the circuit as indicated on the ballast and ignitor diagrams and switch on, the lamp will either start or it won't. 

Ahh ok that's good to hear. I suppose it is always current limited by choke regardless so that does make sense. In that case just now to wait for the actual fixture to arrive. Damn it was surprising to me no one here uses bayonet fittings. But at least all going well it'll be here next week

Ahh I have heard of the heated electrodes for the tubes but I figured an HV kick should've started it. Oh well, live and learn I suppose. Thank you guys for the help with the project. God knows I couldn't have come this far without it so cheers. If there's ever a forum meetup I have to get you guys a beer. lmao

They do have meets in the US, but the only one I know of in the UK is in Cornwall, which is the opposite end of the country for us, so not really feasible as we don't have a car and I'm not keen on long distance driving anyway.

You (or anyone else really) will be very welcome if ever you get this far north, but we're literally miles from anywhere here and the nearest site member we know of is in Inverness, 100 miles away