Ah yes, thank you for correcting me, I should have just gone to bed.

Silly me calculated it by doing Fourier sine and cosine series and then managed to include both the sine and cosine series coefficients into the PF calculation

Of course much quicker would have been to calculate it with PF = |P|/S ... meh.

With both methods I now get PF = 0.95577

Edit:

The first harmonic current is the fifth, at an amplitude of a fifth of the fundamental current.

So a low pass filter would be simple and effective, wouldn't it?