[Spridgets] Metric bolts?

[Michael Rowe]

I have a steering lock assembly that I think is from a '78-79 California car - it has an extra, slate-colored (S) wire and the plug is different size from mine ('74).  The only allen bolts I could find in the hardware store to replace the brake-away bolts were metric, "standard thread".  My mechanic/tutor insists (loudly and forcefully) that there are no metric bolts anywhere on a British car.  An yet, the metric ones were the only ones that fit.  If this lock is not British, I may need a different key blank. Any thoughts?  

Michael Rowe
'74 Midget
Long Island, NY