We tried this last year:
1. Friends live in a converted two-up-two down in a terrace and kept turning their heat on and off
2. We live in a 3 bed bungalow and kept the thermostat at a constant 21 degs c when not in
At the end of last winter we had spent an extra £30 on heating
Ever heard of apples and oranges? Your end result is still correct but really they're not even close to being comparable
The heat loss from the walls of the house is proportional to the temperature difference across the extremities. The time taken to heat the house up (and for it to cool) is proportional to (among other things) the size of the rads, the physical mass of the building and contents etc.
On any two identical houses. te house with constant heating will waste more energy. However the house that cycles in heat will need to be timed correctly in order to prevent the warm-up, cool-down processes being noticable to the occupier.
Points to note - most modern boilers can be running for an hour at a time, but not burning fuel by the ton - they throttle back just to keep the rads at full temp. So you might note your boiler is on for 3 hours to warm the house up but a large portion of that time it'll just be ticking over.
Condensing boilers work most efficiently with their CH return temp <55c, if your rads are too small or your output temp too high the boiler won't condense and so works less efficiently (I believe old boilers worked more efficiently at higher temps, which can confuse). Rads are also more effective with higher temps (again, heating ability from them depends on temp difference - hotter rads = faster heating of room to a great degree).