Thanks for your reply Sue. I also found that a James Moore married an Alice Taggart on January 13th 1776 and I have a copy of the entry in the parish register. It is quite possible that 'Radcliffe' may have been written in error but this may be hard to prove. Your suggestion regarding a will is good and I will explore this. If you assume that Alice Radcliffe and Taggart are the same person then the children do follow in sequence. Elinor (Taggart) 1776, Anne (Taggart) 1779, Samuel and Joney (Radcliffe) 1780, Francis 1788 (Taggart).
According to the LDS I only found 2 Alice Radcliffe's in the Isle of Man that might have been the the Alice I am looking for but they were baptised in the Andreas parish. Still I suppose that these challenges make researching your family tree interesting.

If anyone has any other ideas or comments I would be very grateful to hear.

Pam