Why did Gandalf have a ring?

[narfforc]

I think the reason Cirdan still had the Ring was because he was at The Grey Havens, if for any reason the Elves had to escape, this would be the last line of resistance, Narya would then come into force as a kindler of courage. When Gandalf turned up Cirdan foresaw that it would be needed elswhere. In HoME 12 we are told this:

After receiving a vision of a white boat, shining in the air above him, sailing west

As we now perceive, this was a foretelling of the ship which after apprenticeship to Cirdan, and ever with his advice and help, Earendil built, and in which at last he reached the shores of Valinor. From that night onwards Cirdan received foresight touching all matters of importance, beyond the measure of all other Elves upon Middle-earth.