I'm on a roll now.
After 30+ years of searching I've finally located the riverside meadow where, in the 50's, my parents took us kids to swim in the river so I would like assistance please with this little problem that I have failed to solve since my school days despite countless attempts.
Some little ****e at school told me the below shape can be drawn without removing the pen / pencil from the paper.
I've started in the middle, done the outside semi-circles first, etc etc and still haven't solved it.
Maybe it can't be done (in which case I will next search out that little ****e and give him a well deserved smack in the gob) or maybe someone can crack it for me?