My pick would be 'Waterloo Sunset' by The Kinks. It takes me back to warm/balmy summer evenings staying with my dad's parents in south London.
'9 Feet Underground' or 'Nigel Blows A Tune' by Caravan always takes me to summer term in 1st year hall of residence. It is however 22 minutes long and mostly instrumental so I wouldn't suggest it.....
If on the other hand, if you have 22 minutes and 40 seconds to spare, and fancy travelling back to the early '70's, here's the link
David reclining in a pool a little more recently