Is a Commercial Letting Agent obliged to secure a bond from a perspective tenant before allowing a tenant to occupy a property?

No -- bank guarantee needs to be provided (6-12 months usually depending on tenant covenant) and really up to landlord to decide / do their DD. Would get a 1 or 2 month deposit until guarantee sorted.

Hello John,commercial leases have terms and conditions which are agreed upon prior to the lessee(tenant) taking occupancy.These are drawn up as a heads of agreement.In practical terms an agent should take a bond or bank guarantee prior to occupancy as this is a landlords security should there be a breach of the lease agreement after occupation of the premises.It is in normal circumstances paid prior to occupancy unless landlord has agreed otherwise.