It would need to be 26, QR, and short travel since the bike doesn’t have suspension corrected geometry. The various Suntour ones seem to be the only options – any experiences or recommendations? She’s nearly 50kg so a regular light spring should be enough I’d imagine.

Have a look what’s on the Whyte T403.

Suntour XCR, seem to be 100mm. I need 80 or preferably 63mm since it’s a small bike with a short rigid fork.

air fork ?

Does it need to be new? I’m sure you could pick up a very good “period” 26″ fork for not a lot.

It needs to be available. Air preferable of course, but I’m looking for new hopefully specific recommendations in the budget range.

Put something in the classifieds.   My son has the Whyte 403 and I sourced a Fox 32 100mm for £80.     Took about 3lbs off the weight too…

Sure you could pick up an old set of SIDS in good nick that would do the job or even some Pace carbon forks pretty cheap