Will give it a go thanks, if it has little to do with capacitance, why do you think the apparent current goes up 10% when I start to dim the bulb? I agree that the apparent current seems strange since the capacitance of the lamp wiring I'm currently using is only 500pF, but I thought that it's possible that those currents could be since it's going from zero volts upto possibly three hundred volts nearly instantaneously, rather than following a curve. The other thing that I thought I should try is to only read the current shortly after triggering the triac, currently I'm charging a cap from the opamp and reading this whenever.
Thanks