Law of Property Act 1925

ii That the conveying parties, or the persons deriving title under them, will at all times, from the date of the conveyance, or other date therein stated, pay the balance of the rent (after deducting the apportioned rent aforesaid and any other rents similarly apportioned in respect of land not retained) and observe and perform all the covenants, other than the covenant to pay the entire rent, agreements and conditions contained in the lease and on the part of the lessees to be observed and performed so fax-as the same relate to the land demised (other than the land comprised in the conveyance) and remaining vested in the covenantors:

And also will at all times, from the date aforesaid, save harmless and keep indemnified, the assignees and their estates and effects, from and against all proceedings, costs, claims and expenses on account of any omission to pay the aforesaid balance of the rent or any breach of any of the said covenants, agreements and conditions so far as they relate as aforesaid.