The reality is that it is actually a bit shit. and would cost tens of thousands to retrofit. The compromises that the owners would have to make in terms of either apperance or internal area make heat pumps very unattractive.
The main issue is to add insultation you either do exterior insulation which covers up all of the period features that make the property valuable in the first place (and could lead to complaints from neighbours) and for many terrace houses the space between the front of property and the public street is 0, or you give up interior floor space which even at this price point is actually pretty small already. Both lower the value of the home which for most British people is the primary and often only investment (UK financialisation of housing).
The thing is, heat pumps aren't a particularly good deal right now.
Heat pumps generally have less heat output than a gas boiler, so it won't make your house any warmer.
Even taking government subsidies into account, the installation costs are several times higher than a gas boiler, both for the unit and often requiring new radiators and suchlike.
And typical energy prices in the UK might be 6.5p/kWh for gas, 26.0p/kWh for electricity - so even if your heat pump achieves a 3.0 CoP your running costs are still higher. In the UK, the months when you'll want the most heating are the months when domestic solar output will be at its lowest. To make savings you've got to switch to a plan where electricity costs change several times a day, such as https://octopus.energy/smart/cosy-octopus/ and not run your heating between 16:00 - 19:00. This makes a well-insulated home even more important.
And you might think you're going to save money by not paying the gas supply 'standing charge' - but gas suppliers can charge whatever they like to remove your meter. If they say it's £1500 to remove your gas meter and save you 30p/day - you're probably not going to be saving 30p/day
So it's less a case of "investing" in the house, and more a case of "investing" in good karma by helping the environment.
You can get electricity at 7.5pkWh. With a battery, I get 12h of cheap electricity per day, and the rest at higher prices.
At the coldest time of the year, I'm getting an average of 20pkWh.
This is just a fraction above break even gas/electric.
The rest of the year its no contest, heat pump wins.
My energy usage for heating is down by 60% year on year
My bills are the same as they were 3 years ago.
You need a smart meter. It's electricity only.
You (and I) get £50 credit with this link: https://share.octopus.energy/happy-frog-559
Of course these figures depend on how much of the day the house is occupied, how high the thermostat is set, and how cold the weather is.
[1] https://find-energy-certificate.service.gov.uk/energy-certif...