I posted a message on Nextdoor about this situation:
We had a picnic on Wandsworth Common last Saturday. I go to the common regularly during the week, but I’m usually at the playgrounds, which are dog-free. This time we just found a space towards the middle of the park, under a tree for shade.
During the picnic there were two separate incidents with dogs. The first dog ran up to us, grabbed some bread, but made no attempt to run away. Instead, it continued to lunge at food on our blanket, where my 4 year old, my 2 year old, and my 7 month old were sitting. My husband was very upset. My two older children were screaming. The dog had time to run over to another picnic, where there was a