Leaseholders' Obligations - Gas Safety

There are very stringent obligations on landlords in respect of ensuring that all gas appliances within tenanted properties are serviced annually, but these do not apply in respect to leaseholders. As a housing manager and housing trust board member both tenants and leaseholders living in blocks that we own and manage have queried whether long leases could not be amended to include such an obligation on the leaseholders. Although I know of many public sector landlords who have offered a gas servicing service to leaseholders I know of none who have changed their leases or use any implied lease terms to compel leaseholders to have an annual service carried out.