biro mark on leather couch

oldtimer, I just checked my household hints and tips book and it mentioned a traditional tip - milk. Try putting a bit on a cloth and gently rubbing it. I doubt milk will do it any harm. Just rinse it off in case it smells!
 
Thanks MB05 and sueellen for the tips. I tried the hairspray and it worked perfectly. Biro mark wiped off completely. Again many thanks.