You could use:
=MID("SMTWTFS",WEEKDAY(A1),1) 'A1 is the cell with the date in it
Or if you want a unique letter for each day of the week you could use the
2nd letter Thursday & Saturday
=MID("SMTWHFA",WEEKDAY(A1),1)
or whatever scheme you wish.

On Wed, 15 Dec 2010 22:42:22 -0800 (PST), GavinS
wrote:

In various cells I have dates written in as dd/mm/yy format.

I would like to format this as d - that is the first of the day only.
For example 16/12/10 displayed as T (for Thursday).

How can I do this please