The landlord’s valuer would no doubt say there is no need to be concerned about the difference between the two interests where the landlord is the same especially as the tenant is only concerned with the overall premium payable.
However it is important to differentiate as:
a) the notice has to apportion the amounts between the two landlords to avoid it being rejected as a deemed withdrawal (especially where the lessee serving the notice is assigning the right to an incoming purchaser) ; and:
b) the resulting premium which will reduce overall.
Indeed on advising a client recently with an interest of just over 10 years but where the landlord held from itself an intermediate lease of around 63 years; the effect of relativity on the intermediate interest and deferring the freeholder’s interest by this term reduced the premium range payable by over 5%.