Willow Lake from Little Callow Mound  (Photo © Jagoda Zajac)

Newton Leys is a newly developed and still expanding residential sector of the city, largely built on the site of disused claypits and brickworks. The natural history interest derives from flooded claypits and revegetation of ground disturbed by the clay workings. It was the first time the Society had visited the site and despite evening temperatures in the 30s Celcius a party of about 15 of us set off from the car park of the local centre.

Willow Lake

Our first halt was on Little Callow Mound, overlooking Willow Lake. Formerly named Jubilee Lake, this was the claypit of the Jubilee or Skew Bridge brickworks. It is very deep because of digging down to the Oxford Clay, which has particular qualities for brick-making. Notably, its high organic matter content makes the clay self-combust; known as the Fletton process, after the site in Cambridgeshire where it was developed, this requires less fuel to heat the kilns and produces a higher quality brick.

Brick-making commenced here in the early 1930s, probably accounting for the name, since 1935 was the Silver Jubilee of King George V. The works were later taken over by the London Brick Company.

The Jubilee Works were one of three brickworks in the locality, the others being the Bletchley Works, whose pits have been incorporated into the Blue Lagoon Nature Reserve, and a third on the outskirts of Newton Longville, on its boundary with Bletchley.

Since there was no housebuilding at the time, brickmaking here was paused during WW2 and the kilns were used to store munitions. After WW2 brickmaking really took off, especially with the building of Council Houses. Brickmaking at this site ceased in 1978.

Initially the claypit here was a dry pit. The Jubilee Brook, which flows through the site from a source between Drayton Parslow and Newton Longville and which leads to the Ouzel at Water Eaton, overflowed during the floods of 1947 and flooded the pit. Latterly clay was brought to the site by road from Coldharbour on the old A5.

The other brickworks in the area closed in the early 1990s and their site is used for landfill. Here on the south side of the area we have brownfield housing, complemented by an adjoining greenfield site, actually in Bucks and belonging to the Parish of Stoke Hammond.

The brick-built artwork on the Mound, named Alphonso, is a reminder of the brickmaking on this site and of the many Italians who worked here after WW2. For many years brickmaking was the second largest employer in Bletchley after the railways.

The lake is fringed with a fine stand of Common Reed (Phragmites australis) with Purple Loosestrife (Lythrum salicaria) and Cat-mint (Nepeta cataria) in places. Birds on the water included Tufted Duck and a family of Great Crested Grebe, and flying above the lake were Swallow, House Martin and Sand Martin.

Skirting the lake on its west side took us through a planting of various types of Willow, and Alder Buckthorn (Frangula alnus); the Crack Willow (Salix x fragilis) having been stripped bare by the Red Poplar Leaf Beetle (Chrysomela populi) much in evidence.

Red Poplar Leaf Beetle – Chrysomela populi  – on Crack Willow (Photo © Frank Goates)

We then left the lakeside, crossed the Jubilee Brook, now dry owing to the unusually low rainfall this year, and examined an attractive small wetland. Surrounded by Willow and shrubs, the central part held a notable stand of Common Fleabane (Pulicaria dysenterica), along with Meadowsweet (Filipendula ulmaria), Hard Rush (Juncus inflexus), Wood small-reed (Calamagrostis epigejos) and an unidentified sedge. Wild Angelica (Angelica sylvestris) and Tufted Vetch (Vicia cracca) were found on the margins. Silver-Y (Autographa gamma) and Mother of Pearl (Pleuroptya ruralis) moths were observed foraging in the area.

Foot of Callow Mound

Callow Mound, to the north-west of Jubilee Lake, was formed by the overburden removed from the upper layers of the clay pit. It initially was colonized by a grassy flora classed as Lowland Dry Acid Grassland, a Notable Habitat recognized by Natural England. However, its significance is now reduced since the mound appears to be entirely covered by well-established Hawthorn (Crategus monogyna) creating a closed canopy and a ground layer of False Brome Grass (Brachypodium sylvaticum).

Dragonflies were observed as we walked along the foot of the mound; Migrant Hawker (Aeshna mixta), Southern Hawker (Aeshna cyanea) and Willow Emerald damselfly (Chalcolestes viridis) were noted.

Little Willow Lake

Little Willow Lake is a shallow landscaped feature lying to the north of the local centre. It is fringed by Common Reed (Phragmites australis), Reedmace (Typha latifolia), Hard Rush (Juncus inflexus) and Wood small-reed (Calamagrostis epigejos). Birds included Coot and Little Grebe. Reed Warbler was heard during a previous visit. Along the path on the east side the plentiful Common Bird’s-foot Trefoil (Lotus corniculatus) attracts many bees.

Calamagrostis epigejos fringing Little Willow Lake (Photo © Jagoda Zajac)

At this point of the visit dusk was approaching. A flock of fifty or so Swallows and Martins were over the lake, probably already on passage.

North of Little Willow Lake and across Galapagos Grove lies a third, wilder lake; while the recce showed this to have natural history interest in the form of waterside vegetation and water birds, fading light precluded a visit on this occasion.

Final Comments

On the southern perimeter of Milton Keynes, this site provides some balance to the more frequently visited natural history sites in the northern and central parts of the city.

Although a built residential area, the lakes and green spaces clearly hold natural history interest, as mentioned in this report. Visits in winter might reveal more wildfowl on the lakes. The landfill site might also merit a visit if that could be arranged; this might include the woodland named New Covert on the OS map and which appears to hold some mature Oak.

A notable feature of the site is the extensive amphibian fencing, made of wood and including path barriers. While attractively made, these will soon need maintenance. Work will also be needed on some of the wetland areas and lake margins to prevent scrub ingress and loss of open habitat; perhaps also Callow Mound could be opened up to recreate grassland there.

Amphibian fencing (Photo © Jagoda Zajac)

Charles Kessler and Mike LeRoy, Co-leaders
August 2025