It's simple, you cannot borrow money on a property, unless you have equity in it.
For example, if you buy a £100,000.00 flat, put a £7000.00 deposit down and borrow £93,000.00 you will have no equity, or at the very least a small amount.
The only time you can borrow on a property is if you are in equity, this is usually after you have payed quite a lot of your mortgage off, or when property prices have risen.
Oh and for the record, there is no real 'sponsorship' it's just marketing to get you to part with your money.