[ALUG] Sort dd/mm/yyyy

Hi everyone I have some data like this: something:01/01/1980:something something-else:12/05/1993:foobar another-something:32/01/2012:barfoo etc In other words, it's a colon delimited file in which the second field is a date in the form dd/mm/yyyy. How do I sort the whole file in date order by the second field? I can see that 'sort -k' allows me to pick the positional part of the fields and -t allows me to pick the delimiter. But I can't work out how to combine them so that the whole file is sorted. Thanks Richard