Yeading Brook is the dominant source of the River Crane, in outer North West then West London. The western branch flows south. It rises in the far south of suburban Pinner and drains all of the western suburbs of Harrow, insofar as they have not been by historical practice connected into sewers. Rapidly the brook coalesces at sports grounds associated with and including Headstone Manor, where there is a surviving medieval moat, and leaving the far west of Harrow it makes a large curve to adjoin southern parts of Ruislip then Ickenham Marsh nature reserve, before finishing the more than three-mile sharp curve on the south side of Northolt Aerodrome southwest of South Ruislip railway station. At this point the Yeading Brook's eastern branch feeds in as others have already from South Harrow. The brook bisects Yeading and then forms the traditional border between Hayes and Southall, being superseded by the unlinked Paddington Arm a few metres to the east. The Crane has no authoritative source of its own and so the Yeading Brook – about double the length – forms the upper part of the Crane's river system. Detailed course Yeading Brook rises By far most distantly as the West Arm. Headstone Manor house moat and its tiny feeder is its first visible section. This is within metres followed by other culverts in the associated sports grounds, draining a tiny copse and Victor Road. The moat is fed from the west by 300-metre-long Melbourne Avenue, thus including the south-east corner of Pinner Park – the southwest of which has a small source of the Pinn and northwest of which briefly hosts its main headwater. The Pinn is a separate river system. The roofs, gardens and roads of the southern half of Headstone Lane also drain naturally into the moat or this short feeder. About 350 metres south of the moat in a cemetery the West Arm receives the local suburban road network's surface water drains as exposed as a garden feature of Brook Drive (north side houses) and now culverted as such for Moat Drive (south side houses). The east end of gardens on that side of Walton Road has two discreet sources of these minor flows. About 540 metres SSW a fresh water flow from Harrow Recreation Ground and all nearby streets is received. (or in flow) southwest is sometimes comparable inflow to the above three sources, Roxbourne