If you are a tenant and you wish to assign your commercial lease to another party, you will normally require the consent of your landlord to do so.
Failure to do so could have serious consequences for you including you remaining liable under the terms of the lease. Note the case of E.On UK plc v Gilesports Ltd  EWHC 2172 (Ch) in our case study section. Similar requirements will normally apply under your lease if you wish to sublet your premises.
If you are landlord and your tenant has made an application to assign or sublet, then you have an obligation to deal with matters in within a reasonable time and action may be taken against if you fail to do so. Our commercial sublease team can advise you on your lease obligations and on how you should proceed.