Thanks guys. For my purposes, my main concern is reducing the risk of injury rather than optimising performance - so it's a question of which is more risky, doing a long run on already fatigued joints or not allowing enough recovery time after.

Having read the responses I'm thinking a rest day after is better for me, and I'll try and schedule an easy day before. I don't think I'm at the stage where recovery jogs after a long run will be of benefit to me.