Never dispose of tools!

At the last MoT the van had a notification that the radiator support crossmember was corroded. Not a structural part, but I'm replacing it anyway. Easy DIY job by the looks of it, six big bolts hold it in place. I thought I had every metric socket in my extensive toolkit. Not so, I have every size from tiny up to 34mm, with the exception of the one that fits these bolts, 18mm, not a standard size. Never mind thought I, I also have a vast collection of little used A/F sockets, one is bound to fit. No, the 11/16" is nearest, very tight and would need to be hammered on to the bolt.
Scratching my head, I remembered in the dusty depths of my bench cupboard I have a set of Whitworth Britool ring spanners, unused since my apprentice days. Sure enough my big 3/8W ring fits perfectly... 
Moral, despite what the boss says, never throw owt away, it'll always come in...
Al.