Dear Tudor
Yes -- I do see what you mean. I rather think that this is down to the fact that whoever inputted the data in the first place simply typed the date into the formula bar without first formatting all the cells in the column to be in date format - so Excel thinks that the contents are text.
There is a function within Excel called DATEVALUE which converts a date in text (eg. 03/12/1940) into an Excel date;
Usage is: =DATEVALUE("03-December-1940") (it doesn't seem to understand "03-12-1940")
That seems to do the trick - you might want to play around with that (my Excel skills are such that I personally would paste the whole date column into a one column table in a word document, then do some multiple find and replace operations, and then paste it back into the spreadsheet).
If you're happy with just getting everything into years, then I would suggest you stick with what you have achieved so far. If you would really have it in the correct order within each year (Yeh! I can be a real purist at times!), then you might want to play around with the DATEVALUE function ...
Don't think I'm your man from Ealing - I won an RAF scholarship to (as it was then) RAF Henlow (the whole Biggin Hill => Cranwell selection process), then lost it three months later for medical reasons. So I got myself into the 23rd SAS (lots of unlikely fun) but decided that a career in electronics (and then computers) offered a whole lot more longevity. Then took a BOAC VC10 to South Africa - and never really made it back to the UK on a permanent basis. Such is life! If I hadn't lost the RAF Scholarship I suspect that I would have been a contemporary of BEagle ... But there you go ...
Feline Felicitations ...