Out of curiosity are these insurance premiums you're quoting TP, TPFT or fully comp? £1850 insurance for a 172 sounds incredibly low for a 17yo who's only just passed their test. In my past experience many insurance companies wouldn't touch you for this car, let alone for (only...?) £1850!
I'm not 17... That could be why. All fully comp quotes.
Now can we get back to quoting me some cars, instead of questioning insurance. I'll deal with that after.