HO 107/726 is the reference for the Hundred of London Without The Walls, parishes: St Bride or St Bridget & Precinct, (Bridewell Hospital), St Dunstan-in-the-West and Serjeants Inn, Fleet-Street, according to the National Archives. This is in the centre of London, somewhat east of Kensington. If this reference is correct, you might want to check old maps for this region to see if you can spot something that might be Hevells Court.
What was William Curtis' occupation? 1841 historical directory shows a William Lamb Curtis, salesman, 25 Newgate St - which is near the area shown and there is a Lovell's Court just nearby, off Paternoster Row (Newgate St being perhaps his work address, Lovell's Court being home?)
The other thing to do would be to go back to the 1841 census sheets and check nearby households to see what other streets were in the vicinity, as this can help place people when street names are difficult to read.