Most private landlords used to take a deposit, usually to the value of a month\'s rent until the government decided that they were being unfair in the majority of circumstances and not refunding them at the end of the tenant to deserving tenants. They decided to combat this by insisting that deposits were protected by one of the following:

• Sending the whole amount to the DPS (Deposit Protection Service) A government authorised scheme whereby the money is held in and account until the end of the tenancy at which point it can be claimed by the landlord if sufficient evidence of arrears of dilapidations can be proved. 
• Paying and insurance police to MyDeposits in order to keep the cash in your bank account

Landlords that do not use either of the above are liable to face heavy fines. 

Benefits to asking for a home owner guarantor:

• You have a second point of contact throughout the tenancy with a home owner that has a vested interest in the tenancy running smoothly.
• The liability of the guarantor is unlimited, a months rent as a deposit doesnt go far if your property is trashed.