What is the purpose of Mrs. Harris’ visit to the headmaster?

Mrs. Harris has come to see the headmaster of her son’s school to ask his advice about her son’s further education.
M: Good morning. Mrs. Harris. Do sit down. I understand you’d like to have a word with me about William.
W: Yes, that’s right, headmaster. I hope I should see you as soon as possible before William does anything he’ll regret.
M: Regret? Mrs. Harris?
W: Well, you see, he has his heart set on becoming an artist. My husband and I think he ought to take up something more secure. I mean even if he went to art school, there would be no guarantee that he could get a good job afterwards.
M: He could probably teach, Mrs. Harris.
W: He wouldn’t like that. He says he wouldn’t be a teacher if it were the last job on earth. Oh, ha, beg your pardon, headmaster, I didn’t mean...
M: Not at all, Mrs. Harris, I wouldn’t have been a teacher myself if I’d had my way. I’d have been an actor if my parents had let me. So I have some sympathy with William’s problems. Now, let’s see, if he wants to be an artist, he’ll have to decide what sort of artist he wants to be.
W: I don’t quite follow you, headmaster.
M: Well, choosing a major can be a tricky endeavor that requires a great deal of planning. What I mean is if he wants to be a commercial graphic artist or cartoonist, that sort of thing, he might do very well if he took an art course at a technical college. And besides, the entry qualifications wouldn’t be so stiff. On the other hand, if he wants to go to one of the major art schools, you’d better not raise his hopes too high. There’s a good deal of competition to get accepted. And he’d have to have at least three O levels and two A’s at good grades before he’d even be considered. Oh, and there is another thing, he’d have to do a year’s foundation course first, probably at another college. He’d get a grant of course, provided he’d got the right O’s and A’s. W: But art, headmaster, it’s so chancy.
M: I don’t think you should stand in his way, Mrs. Harris. If I were you, I’d let him decide himself. You’d better accept the fact that nowadays young people don’t worry about security the way we did when we were young. Hobbies are often a predictor of what one should choose as his major. It is great that your son starts identifying his passions.
W: Well, I must admit my husband and I would’ve felt much happier if he’d chosen to do something else. Perhaps it’s still not too late for him to change his mind. You know, I could get him a good job with my own firm if he had a science degree. You know, and future possibilities... a great salary, opportunities to make a difference in the community, and supporting...
M: From what I know of him, Mrs. Harris, I don’t think he’s the sort of boy to change his mind, not in a hurry, at any rate. In any case, I think you ought to let him decide. Let him focus on his strengths and stick to what he is good at. If he enjoys art, don’t force a science major, or it will probably prove disastrous and he will end up changing later anyway.
W: But an artist, headmaster, what’s he going to live on?
M: Making a career as an artist isn’t easy, of course. But William’s always been interested in painting; you know that, and this field will give him the opportunity to live out his dream. It would be a good idea if you had a talk with your Art Master Mr. Simms. He can tell you more about the possibilities than I can. I know he thinks very highly of William’s work, though you’d better not tell William that I’ve said so.
W: I suppose I shouldn’t worry so much, headmaster. But I can’t say I like the idea—painting pictures and that, it doesn’t seem like real work to me.
M: On second thoughts, I think the best thing would be for me to have a word with Mr. Simms first and find out what he thinks of William’s chances of being accepted at art school. It’s a very liberal training, you know, not just painting pictures.
W: No, of course not. Thank you very much for your advice, headmaster. I’d be grateful if you let me know what Mr. Simms says.
M: I’ll do that, Mrs. Harris, and in the mean time, don’t worry about William. He’ll be all right so long as he does as well as he’s doing at present.