speaking rationally, it seems that the calculation was that any illness jo roswell had was mild enough that it would be a greater risk to change the line up than to have jo ride.
speaking as a norn irishman, however, it is clearly another example of the mentality of imperialist brits who are happy to exploit the labours of our wee country (eg Titanic, DeLorean, Rory McElroy) when it is in their nefarious interests to do so, only to give us nothing but the blame when it is time to pay out.
three sucess stories for the irish !
;-)