So my mate came round and we managed to jump start the car after a few minutes of having the leads hooked up. It did take a few attempts but was then fine... So I thought "it's the battery." Went to the shops today and bought a new one, brought it home and hooked it up to the old battery to jump start it again. (If I fit the new battery then I invalidate the guarantee and can't return it if it turns out to be something else, hence using the jump leads.) With the new battery connected via leads, I'm back to the clicking sound... This is driving me mad, I only just bought the car a week or so ago and wonder if the guy sold me down the road

Starter motor???

I'm thinking to get a mobile mechanic to come and run a diagnosis - thoughts?
Ta