I'm curious as to know what exactly 'he twirled at the pin' means. The phrase appears in numerous songs.

It invariably occurs when our protaganist is approaching a 'maiden's bower' and can obviously be updated to 'he rang the doorbell'

My query is, what exactly is a 'pin' and why would you need to 'twirl' it?

In the DT database, a modernisation is given for the song 'Glenkindie' the meaning being explained as 'turning the latch.' However, in most songs, twirling the pin, seems to be an attempt to be heard rather than a way of sneaking in.

My dictionary, which is usually pretty good at giving archaic definitions, doesn't help.

I could understand ringing at a bell, or a bell-pull. But a pin?

Any ideas?

Thanks

Ed