Can't attend work on account of religion.

[Yachtie]

But maybe the person can only do that type of work and, presumeably is not from a 'mainstream' (in Ireland anyway) religion, has little choice in the way of jobs ?
The person should have brought this up at the interview, but if rejected could possibly have claimed religious discrimination. Maybe thats why religion never came up at that time.

Flexibility from everyone involved is the only approach I'd recommend.
For example, if other colleagues took turns to cover for that person on Thur/Fri, and that person then covered for his/her colleagues at other times ?

This person is a Muslim as in Islam, Friday is the equivalent of Sunday for Christians. They can pray wherever they like, a trip to the mosque is not mandatory as long as they are facing Mecca. The direction can easily be established on one's own and I think this person is avoiding his professional duties by means of abusing his religious belief.

 

[ClubMan]

Is a Lepricon some kind of unicorn?

No - it's a rip-off skin disease.

 

[Brendan Burgess]

and on that note...