I think Margaret has always been ready for anything. I tried to sit next to her at dinner parties and get my hand as far as possible up her legs without others at the table becoming aware.
Sometimes I got to her panties but had to stop as her facial expression would have given us away.
At dances I would take the opportunity to press against her, my dick being hard. She loved it.
Then she got her own back. A group were away at Centre Parcs. We had been there a day or so, when Margaret suggested that she and I go for a swim in the pool. The others did not want to come, so we were alone together. When we got to the pool, Margaret mentioned that they had family changing facilities. This sounded like fun!! We found a cubicle and both of us started to strip. I had barely taken my underpants off, when Margaret grabbed my dick and started to jerk me off. Wow, such an unexpected opportunity. Two minutes and I was ready and grabbing for my towel. Margaret immediately suggested I use hers and into that I shot my load.
Well the swimming afterwards gave me some chance to repay the favour. But not enough time, without others around, to bring her off. I don't think she cared, she wanted to see me cum!!