I am aware of the traveller encampment at 39 West Barnes Lane, Raynes Park, which is creating a significant amount of disruption and fly tipping.
Raynes Park councillors and I have been in regular touch with both Merton Council and Merton Police about this and they are working with the land owner, who is seeking an eviction order via the courts. It appears that, as the encampment is on private land, there is not much the Police can do at present.
The Government is currently reviewing the powers to deal with unauthorised caravan sites and consulting on this until 15 June. If this is an issue you feel strongly about you can find out more and respond to the consultation here: https://www.gov.uk/government/consultations/powers-for-dealing-with-unauthorised-development-and-encampments