Single Metal Pin For Ikea Chair (PL4)

Hello I have an IKEA chair which I got for free, it was missing most of the fixings which I've now replaced but it's still missing a single metal pin like shown in the provided photo.

The dimensions are:
Length 50mm
Thickness 0.8mm (M8)

If someone had one of these they willing to let me have I would be most grateful for it as I am unable to use the chair without it.

Thank you.

I'm in the PL4 Greenbank area.