The South Staffordshire MP said the pitch fee review inflationary index uses the Retail Prices Index (RPI) to calculate the maximum annual increase for pitch fees.
But park home owners and other campaigners, along with Mr Williamson, want the Consumer Prices Index (CPI) to be used as the basis for the calculation instead, which would result in lower costs for park homes owners.
Despite the Government promising to change the pitch fees index when Parliamentary time allows, no Bill has been scheduled.
Mr Williamson has also called on the Government to support local authorities in enforcing the "fit and proper" test for park home site owners and managers.
The fit and proper test is used by local authorities to ensure that the owners and managers responsible for managing park home sites are free of criminal convictions and of good character.
Sir Gavin said: “Park home owners can be uniquely vulnerable in their living situations and deserve proper safeguards for their pitch fee increases and the quality of their management.
“Given the inflationary pressures everyone is experiencing currently, it is especially essential the Government moves quickly to put a change from RPI to CPI into law to help park home owners in South Staffordshire and right across the country.”