I’m 30 so not the oldest or the youngest but I had my first OSF at 7 years old which was a yellow mk2 Escort 4 door that I paid £50 for, with the intension of running it round the field next to our house but my uncle said that it was too good for that so we did some work on it and put it back on the road for my granny and that’s where I got hooked on OSF's and learned the basics grinding, welding etc
And I ended up getting my granddads old mk1 fiesta to rag around the field instead