Free boiler replacement still available in London via ECO energy grant scheme
Government energy grants for free boiler replacement are still available via the ECO (Energy Companies Obligation) replacement boiler / central heating scheme.
The grant criteria, which can be found here - free boiler application.
Providing you are either a home owner, private tenant or landlord, and your existing gas boiler is not of the condensing gas boiler type, if you meet the qualification criteria above you could have a new gas boiler system installed completely free of charge - with absolutely no cost or payment required.
More info at Free-Boilers.org.uk