Concerns amongst residents were reignited after travellers returned to Stanmore Marsh just weeks after they left the site.
The travellers repeated return to Stanmore sparked a community group to be started with the travelling community returning on July 28.
They were quickly issued an eviction notice by police and council officials and by 30 July they were gone, again.
However, Harrow Council have since installed huge boulders to make access harder for travellers to enter Stanmore Marsh.
The latest encampment follows a similar one behind the library which left the owners with a horrific clean-up bill totalling more than £92,000.
The Stanmore Society is now urging locals to start Friends of Groups to help protect the areas green spaces.
Michelle Chalibamba from the group said: “Unfortunately, some unwanted visitors recently had their eyes on our magnificent green spaces.
“To ensure that we maintain these amazing assets each park needs to form Friends Groups. The Friends of Bernays Gardens are doing a tremendous job renovating and returning the Gardens to their former glory.
“Now it is time to do the same for Stanmore Recreation Ground.”
If you are interested in getting involved, please contact Michelle on firstname.lastname@example.org