madness in hyde park 2

i stopped taking peppa to hyde park off-lead in the weekends as she loves inviting herself to peoples picnics last time she was dining on sushi before i got her and she loves nicking balls and flying plates but not retorning them (if theres something left)  my pup is a thief!!
so today it was about to rain and the park was relatively empty so i gave her a good run. there was arab couple under a tree with some food with them she run towards them and the stupid guy started running for his life as he was being chased by a hungry lion in his socks! it was so funny even his girlfriend laughed and i wasnt sure if its a joke or not but i tried to stop her and told him to stop running if he want her to stop she was totally in the chase and barking but he was too terrified and eventually lost balance and fell on the ground and i felt so sorry for him and apologised million times and put her on the lead again.
shes allowed to be off lead there and her recall is good but how do i prevent similar situations in the future? firm no and putting her back on lead only work for short while as the temptation of food/balls/people is too much for her .
i dont need trouble the guy today could have complained.

Have you considered using a long training lead ? This way you have control and Peppa still gets to have a run around, just let it trail within your reach.

Yes training lines are great   

i might give it a try but i still want her to behave off-lead cause her recall is good and most of the time its enough when i say no. but not always...
so what training lines do you recommand?what length?

I have a 50f and a 20f   

http://www.ebay.co.uk/itm/DOG-HORSE-TRAINING-LEADS-5FT-10FT-15FT-20FT-25FT-30FT-40FT-50FT-65FT-80FT-100FT-/140987430180?pt=UK_Home_Garden_Kitchen_Steamers_Cookers_PP&var=&hash=item20d3817524

A long training line is so much better - she'll get a great run, still work on her recall and you'll avoid situations like that thatjust contribute to giving the breed a negative stigma

We use a training lead 90% of the time and Bane's recall is really starting t improve from using it! When we call, most of the time he will come back before we have to tug the line.
We find it works better used with a harness though as it doesn't put any pressure on his neck if we have to pull him away from something/one