I am not a teacher.
The name Cecil is pronounced /ˈsɛs(ə)l/ in BrE. I noticed the strange pronunciation of it in this film too, where it sounds like /ˈsiːsɔːl/.
The tip of the tongue touches the palate just behind the front teeth when pronouncing 'l', and is pulled back and down to pronounce the 'aw'. At least that is true of my variety of English.
Note that there are native speakers in Britain who pronounce the final 'le' in words such as little, bottle and so on, in a way that resembles 'aw' with the tongue in a sort of mid-position. This is not standard.
Student or Learner