BEagle, anyone that's up for spending several thousand pounds getting a PPL is not going to be put off by another £450.
In the scheme of the overall costs incurred learning to fly paying instructors and extra £10, or £15 if you like, an hour isn't going to make any difference at all to the punter. If it does then they're not going to be able to afford to keep up with flying once they've got their PPL.
Obviously cost is a major factor in deciding whether or not an interested party takes up flying but let's not kid ourselves about a few hundred, or a thousand, here and there. It's an expensive game and additional expense needs to be viewed relative to the existing expense.
Of course none of this changes anything because there will always be someone ready to step in to do the job for less thus keeping down everyone else's pi$$ poor pay packet. As has been discussed at great length.