Rent aside (and it seems ridiculous if the rent psf being demanded is higher than East Dulwich), it is not that unusual to have a lease for more than 2 years in respect of commercial premises - in fact, I'd say the norm is 5 or 10 years with a tenant's break option.

Equally, I suspect the "year's rent up front" is a rent deposit, which again, is pretty standard fare, particularly if we're talking about a start up with little or no accounting history.

Landlords want to let their premises but they also want, and need, their rent to be paid. They also want continuity and would rather not have the hassle of having to enter into renewal negotiations every 2 years (if it's a 2 year lease) if they can let it to a good tenant on a 5 or 10 year lease.