On Mon, 2 Jan 2012 03:14:19 -0800 (PST), Seanie wrote:

I have the following formula that produces a Date / Time value
BF1+(540/1440) eg 02/01/2012 09:00

What I wish to do is modify above that if BF1 equals any dates listed
in a named range "Holidays" then the formula would change to
BF1+1+(540/1440)

Its the bit on looking up values in the named range that I can't work
out

In general:

=BF1+SUMPRODUCT(--(Holidays=BF1)) + 540/1440

But also take a look at the WORKDAY function.