The old man is Mark Williams who, as mentioned, played Arthur Weasley in the Harry Potter films. Since 2013 he's been starring as the crime-solving priest Father Brown in the daytime BBC series of the same name. The hiker is Paul Whitehouse who co-starred with Harry Enfield in his various BBC series. He was in "The Confection" sketch that you recently watched and was also in "Women Know Your Limits!"
The Rambling Hiker sketch is a classic. Mark Williams is brilliantly hilarious as the old man. LOL at 1:36 2:28 2:45 2:53 3:45 5:03 5:33 5:47 6:03 6:23 6:28 and 7:31. 😆