Hi all,
Many thanks for the replies. Those of you who said reversed polarity were correct. After much digging in the attic under floor boards I found a junction box where the polarity was reversed on load cable coming from the pull chord, cables very badly made off too might I add.
I haven't found out how long this man is without a shower, because I don't see how the previous shower would have worked either.
Either way, shower is now operational. I have offered to inspect the house at a discounted rate, as the owner is an elderly gentleman who lives on his own with very limited social contact.
Thanks again for all your help guys!