Shikra or sparrowhawk?

For the past two-three days, I have been waking up to a call of 'kichew...kichew'...just outside my hostel window. There, on the neem tree, was a little hawk...so familiar in IIT, and yet so unfamiliar to me. For I have been trying to correctly identify what this is. It is quite common in the woods around IIT, and I have even seen it capture mynas. It made a typical 'wing-tent' on the ground around the captured myna...I am almost sure it is a sparrowhawk. It is either a shikra or a sparrowhawk (besra or eurasian). Sometimes it has the characteristic greyish-blue shikra back, but sometimes it is brown. The bird on the neem tree looks superb through my binos.
Even Salim Ali's book mentions it is difficult to distinguish between the sparrowhawk or shikra.
Any suggestions anyone?