Keeping Boiler Maintained For Improved Efficiency

I live in a fairly large 4 bedroom detached family house on a very attractive estate.  We bought the house nearly twenty years ago and at the time, it was considered to be one of the premier styles of house you could buy.  We’ve always been very comfortable and with the radiator central heating, never chilly.  We tend to take this luxury for granted – the boiler is still the original installed at build – I have a service contract with a local family firm who know my system well and carry out an annual thorough clean and of the boiler, they bleed the radiators and check the ignition of the gas fire.  The thermostat is sat in the hallway and for years had always been set just above 22 degrees C.   Every radiator in the house has thermostatically controlled valve so I can turn down any in rooms I don’t use often and rank it up for visitors. I have reduced my overall thermo setting to just under 20 deg C to help reduce my personal use of power and my utility supplier fitted a smart meter two years ago and replaced all my light bulbs with hi ecoomy LEDS.  These are only tiny gestures but it’s a start!