But I was surprised to see there's another Mill Hill. This one's a peak in the middle of Barnes Common, nowhere near the better known suburb in Barnet, at least according to a triangular symbol on OpenStreetMap.
I wasn't aware of a hill in the area, indeed Barnes is well known for being fairly flat. I checked on an Ordnance Survey map and there were no local contours at all. I checked on a topographic map and there was no evidence of significant variation above sea level. So I went along to Barnes Common to take a look for myself.
This is where Mill Hill is supposed to be, a patch of woodland just off the main road a few minutes from the railway station. No obvious hump was apparent. The precise point's in those trees so I left the obvious path and followed a brambly track into the wood as far as the supposed hilltop. It was not there. I found ivy-clad trunks, holly with berries and thick undergrowth but not even a mound, let alone a hump. There is no hill at this Mill Hill.
This 'hill' has been on OpenStreetMap for almost 16 years according to the data in the underlying changeset. I wondered if it might be a deliberate error introduced for copyright reasons, but OpenStreetMap is crowdsourced and free-to-use so it can't be that. I wondered if a local orienteering map might have further information, the Common being a perfect spot for a competitive run-around, and that suggested this spot's actually a slight depression. All things considered I think it's a mistake that's been hiding in plain sight since 2010, and may not survive until the end of 2025.
But there is a Mill Hill here, as you may have spotted on the earlier map, about 200m to the northwest. So I went there instead.
It's a real peculiarity, an enclave of ten large houses adrift on the common and surrounded by trees. It's almost precisely square and impossible to walk into the centre, each house presenting a gated and/or walled frontage to the world. Weirder still three sides have a narrow road alongside where residents get to park and the fourth is a main road where they can't. According to a sign the maximum speed is 10 MPH and according to a fingerpost the loop is a "public byway open to all traffic", so I wouldn't recommend more than 5. It's an impressively defensive site, a huddle of twisty chimneys and gothic turrets all with a multi-million pound price tag. And it used to be a windmill.
There's been a windmill here since the 15th century, because even at only 28 feet above sea level it's marginally the highest ground in Barnes. It's been sequentially a post mill, a smock mill and a tower mill, the 1740 version having been blown down in a hurricane. Shortly afterwards the miller was permitted to enclose a patch of common measuring 260 x 267 feet, and all the subsequent housing has remained within this footprint. The oldest is Mill Hill Lodge which contains part of the miller's cottage, and can be found on the western side of the residential island where the rest of the listed buildings are. The mill was finally demolished in 1838 so don't come expecting a romantic view, just a Neighbourhood Watch poster and a square of well-hidden real estate.
It may only be a hill by default, its elevation barely distinguishable amid the surrounding dog-walking territory. But it is officially a second Mill Hill, and if anywhere needs a little triangle on Open StreetMap it's the gatepost in the above photograph and not the flat bit on the common.
n.b. There is potentially a third Mill Hill in Acton, so I went there too.
It started out as Mill Hill Fields, a cattle meadow on the banks of the Stamford Brook where it's thought a windmill once stood. In 1809 a City lawyer bought the land and built a grand mansion called Acton Hill House, "a beautiful estate with a fine avenue of elms". In 1877 the estate was sold to Chislehurst builder William Willett, he of Daylight Saving Time fame, who covered the site with his trademark smart gabled houses. The ornamental garden of the former manor house became the local tennis club and survives today as a tiny park scattered with playground equipment, unlocked at 7.30am daily. And all this now forms the Mill Hill Park conservation area because Willett's project was called Mill Hill Park, indeed the local station was originally called Mill Hill Park rather than Acton Town. So although its streets are very pleasant I'd argue it's not really a proper Mill Hill... just the two are sufficient.
