I promised that I would try to write about this later conversation after our disastrous car journey.
That evening, some hours after we got home, Mum and I were alone in the house and were sitting chatting. I thanked her for driving me home and said that I was sorry, though, that we had such an awful journey. I said that my tummy had only just stopped hurting after all the strain of holding my wee, in the end to no avail. Mum said that at least nobody knew what we had done. Then to my surprise she said "When did you last wet yourself?" My mind went straight back to the last time - only about a year before. I was walking home with another girl student after a party at which there had been quite a lot to drink. It was very cold which didn't help. I was bursting and suspected from the way she was walking that my friend was too but neither of us liked to mention it. Anyway, I started to leak a little bit in my knickers and then suddenly could not hold it anymore. I was wearing black trousers and I'm afraid I just wee'd in them as I kept walking, I couldn't help it. When we got back to college, I hurried to get to my room. Fortunately with black trousers it was not obvious unless you really looked. I blushed a bit as I admitted this incident to Mum. She was clearly interested and wanted to know if I had done it other times. I said I had done it once when I was about 14 but otherwise not since I was a little girl. Mum then went on to say that it probably happens quite often but we don't see it. She then talked about several times over the years when she had wet her knickers and also about two other women whom she had known do it. She surprised me by saying that there is something excitingly naughty about knowing that as a grown woman you have wee'd in your knickers. I must say, I was starting to feel a bit turned on by this. In bed later, I went over it in my mind. You can guess where my hand was and what I did with it! Since then, on a number of occasions when I have been needing to wee I have just let it happen in my knickers. I don't do it that often but it is always exciting and, either then or later, I bring myself to a good orgasm.