| Law Brook | |
| Name Other: | Postford Brook |
| Subdivision Type1: | Country |
| Subdivision Name1: | England |
| Subdivision Type3: | County |
| Subdivision Name3: | Surrey |
| Subdivision Type4: | Borough |
| Subdivision Name4: | Guildford Borough |
| Discharge1 Location: | Albury[1] |
| Discharge1 Min: | 0.05m3/s(4 August 1992) |
| Discharge1 Avg: | 0.11m3/s |
| Discharge1 Max: | 0.8m3/s(15 September 1968) |
| Source1: | Gasson Farm, The Hurtwood and sources in Peaslake proper |
| Source1 Location: | Peaslake, Shere, Borough of Guildford |
| Source1 Coordinates: | 51.1839°N -0.4439°W |
| Source1 Elevation: | 148m (486feet) |
| Mouth: | River Tillingbourne |
| Mouth Location: | Colyers Hanger, Albury (foot), Borough of Guildford |
| Mouth Coordinates: | 51.2222°N -0.5167°W |
| Mouth Elevation: | 50m (160feet) |
| Progression: | Postford/Law Brook - Tillingbourne - River Wey - River Thames |
| River System: | Thames Basin |
The Law Brook or Postford Brook is a stream in the Surrey Hills AONB which feeds the Tillingbourne which in turn feeds the River Wey. It is notable in its own right chiefly for its industrial vestiges and records.
The stream runs, WNW then north, about in the Vale of Holmesdale (a mainly geological term explaining the axis of the basins of the Medway, Mole, Tillingbourne and Wey, west branch). It mainly rises in the former manor farms and common land of Peaslake on the northern slopes of the Greensand Ridge. It drains much of the northern Winterfold Forest/Hurtwood: the upper half of the drainage basin is forest with some pasture save for the large hamlet itself. The stream waters the clustered village of Brook/Little London in Albury. On the left bank the stream has, after its coalescence of headwaters, the northern lands of Farley Green (the secondary village in Albury parish) then briefly a low corner of Blackheath, Wonersh - a sparsely-inhabited wooded plateau, on the opposite bank of the closest-to-village fields of Albury's main settlement, including a further former millhouse.[1]
The last demarcates the land (parish) of Albury from St Martha, centred on Chilworth.[2] [3] It and the Tillingbourne were harnessed by digging leats (narrow cuts) and mill ponds for industrial mills - the Royal Gunpowder Mills, a long leat dividing Chilworth and supplying its largest pond, known today as The Fish Pond.[4]
The North Downs Line follows a distant right bank of the Brook for along the width of Albury's essentially rectangular parish.