Firstly may I thank everyone for such great responses.

I've given the method using the Excel modules a go, but I think it is a
little beyond my ability with Excel at present. Basically I'm not sure
how to input the data into the module, so I just get the "#VALUE"
coming into the cell whenever I try to use it, even when I try copying
and pasting in your example as follows:

? Convert_RA2DecDeg("03 00 00","HH MM SS","double") yields 45

though it does complain about the question mark, so I'm sure I'm doing
something wrong. If you could give me a bit of an idiots guide
regarding how I input a piece of data into this module that would be
great.

The method of using the LEFT and RIGHT functions in Excel was also very
intriguing and works great for getting the degrees and arc seconds out
of a coordinate. However, I'm unable to get the arc minutes by itself
because it is in the middle (i.e. I either use LEFT (J2, 6) and get the
first 6 characters which includes the degrees bit as well, or RIGHT
(J2,6) and get the arc seconds bit). Is their something really obvious
I'm missing with using this function? Could their be a MIDDLE
function or something like that?

Kind Regards,

Matt