4. Smooth barked tree, whose fallen foliage is notorious for its persistence (5)
8. Has it a flaky bark? This must be the flight to Heathrow (6, 5)
16. What Andy Murray may deliver occasionally? This tree occurs locally and often in association with 7 which is a small leaved lime (4, 6)
Small-leaved Lime (Tilia cordata) and Wild service tree (Sorbus torminalis) are indicators of encient woodland and are often found together in that habitat.