Under LTA 1954, T’s s25 notice (and, indeed, many other significant notices) must be served by T on the ‘competent L’. That person is defined as the person with the ‘legal estate’ (s44(1)). 


Problems arise if L’s interest is transferred, and there is then an interim period before the transfer is registered at the LR (ie there is a ‘registration gap’ between the sale of L’s interest, and the date when the transferee is registered as proprietor). During that ‘registration gap’ period, any s25 notice should be served on the original L (ie the transferor – who is still the registered proprietor), rather than the transferee (who merely has an equitable interest until such time as registration is completed).