STOP ! DONT SPEND 100 QUID
I have just spoken to 2 local steel merchants / suppliers.
There is no such thing as high tensile stainless steel.
There are 2 grades of stainless steel A2 and A4.
A4 is the marine grade stainless steel which just so happens to be higher tensile steel than the standards A2 but is not as high tensile as Hight Tensile steel.
It is perfectly possible that the mention of High Tensile Stainless is refering to A4 marine grade stainless.
Any way DUTCHY FASTENERS (01872 573999) (http://www.duchyfasteners.com/
) have M12 100mm A4 Grade stainless bolts for around £2 each in stock.