Hi Machair, No you are not the oldest! I was still having regular and heavy periods at 55 but these stopped when I was put on the mini pill-at the time given as birth control as I was in a new relationship and was told by my G.P that pregnancy was still a remote possibility!!
The pill actually stopped my periods and 6 months later I went on to hrt which gave me a monthly bleed. After a year my GP changed this to conti hrt, but I still had breakthrough bleeding from time to time so not sure when periods actually stopped completely..I'd estimate 57ish. So you may have a way to go yet!
D&P