I am no expert on this but don't think it's as simple as direct price comparison. I have gas from a bulk tank and don't feel it is overly expensive. I also use it for the hob as I like gas cooking. The main difference I notice between my house and another family member with oil boiler is that I never have to move the dial past 1 to get sufficient heat, the dial goes to 5 and I can't imagine what happens if you put it up that high. If I want a really hot tank of water or roasting heaters to dry clothes or something I might put it briefly to quarter past the one but no higher.
The other house with oil always has their setting to half way on their controls with to me no extra heat or water than I have so while they may be paying less for the oil than I am for the gas I feel they have to use more of it to get the same result.