Fairly well insulated, but it's detached (so no shielding from neighbouring houses), and south facing with large windows (blackout blinds have helped)
I've actually spent a reasonable amount of time looking at what is drawing and when, and can tie most of the changes in use to when people get up and their habits, for example minimum load is around 100watts (networking etc), but then because there are people in all the time the fridge gets opened at least once or twice an hour ruining it's efficiency (it's A rated, fairly modern but kicks in a lot because of it being opened), two computers which seem to use about 150-200 watts each (inc the monitors) when not gaming, a TV in the lounge that uses around 100 watts.
It's literally the fact there are 3 people in the house, and they're in separate rooms much of the time** that makes up much of the use, then an electric cooker and hob that can easily account for 3-4 units when doing meals if say the steamer is used (the oven uses around 2.5kw to heat up then drops to around 100-200 watts, but the hobs use something like 2-4lw each almost constantly if on). I can see on the usage meter for the solar/hourly data on the smart meter exactly when the draw changes and by how much.
I dread to think how much worse it could be without LED lighting, as my dad's eyes are bad enough that he needs really bright light a lot of the time, going back 20 years he used to have something like 6-10x 60 watt bulbs in his living room, modern LED's pushed the wattage needed down to ~20 watts (with a very bright lamp just behind his chair which has a 100watt equivalent bulb at the recommendation of the hospital for when it's needed).
It's the reason we got solar fitted, we know our usage is abnormally high due to there being three adults in the house most of the time and it made sense (it's cut our reliance on the grid by around 80%, we're currently exporting more than we're importing).
*The sun is hitting the large windows pretty much all day, even in the winter the front bedroom upstairs can be overheating at times, it's a typical 70's build, so no insulation between floors, but we've double glazed it, had cavity wall, and loft insulation done.
**Space is needed to maintain sanity