Looking for a Bolt!

I'm appealing to the collective wisdom of the list to solve this
one. I need a bolt. Two would be nice. It's somewhere
between a 3/8 nc uUS thread and a M8 (8 mm diameter)
1.25 pitch metric. I believe it to be Whitworth, or something
similar. I'm restoring an old British Lambert racing bicycle
and these are (or would be) the crank bolts.

I would like to know a) what the correct size is likely to be, and
2) where I might find a pair.

Thanks in advance ...

chuckc@attglobal.net