My imagination is now trying to devise reasons for you to have to flee trouserless through Cambridge...

The trick with that nylon rucksack webbing is to melt the ends with a lighter or a gas cooker before sewing. They have fancy hot cutting thingies in outdoor shops that seal the stuff as they cut. Leather should last ages if you look after it, though - get a tin of leather food or leather oil or something (not saddle soap) and give it a coat once in a while, especially if it gets wet.

Melting the ends: yes, I did wonder if I should have done that, but not quite enough to make a new one in order to try it :-)

Heh - my invariable problem with handcrafts as well :)