SteveG - there are some versions where "Ilo" appears unaspirated. For instance, William Fender sang it for Carpenter as "Eye-low"

However, another of Carpenter's sources, J S Scott of London, does aspirate it, but varies the vowel sound, singing both High-low and Hee-low in the same line:

Tommy's gone to Liverpool
Highlow, Heelo
Tommy's gone to Liverpool
Tom's gone to Heelo