Down:

1 Herschel, 2 acer, 3 stimulus, 4 Battenburg, 5 Robert Peel, 6 Eildon, 7 Who Framed Roger Rabbit, 8 Mearns, 9 Foreigner, 10 The Right Stuff, 11 frère, 12 Space Invaders, 17 And Then There Were None, 22 Aga, 23 soporific, 24 fava beans, 26 Inverness, 27 To This Day, 30 Ashley Walters, 31 Rae, 32 The Jungle Book, 33 Dud, 38 ulceration, 39 LHR, 40 James K Polk, 41 Sandy Lyle, 44 Scotsmen, 46 overwear, 48 Leslie, 50 Briton, 51 seedy, 56 Dawn.