Blue Lagoon


These former clay pits and surrounding land have been sensitively managed and turned into a Nature Reserve which is particularly rich in wildlife.

Banded Demoiselle

Banded Demoiselle

The main feature of this Nature Reserve is a large, deep, water-filled pit (remaining from the former brickworks) which gets the name ‘Blue Lagoon’ from the water which turns a magnificent shade of blue in the right light. This and the surrounding land were designated a Local Nature Reserve in 1994.

The lagoon is bordered on the north by a disused branch line railway, on the east by the main west coast railway line and on the west and south by disused brickfields. Water Eaton brook flows from west to east across the northern sector and various ponds, some with boardwalks, are readily accessible by good solid pathways which link the scrub, woodland and grassland meadow features of the site.

Site history

The Blue Lagoon lies on part of the former site of the London Brick Company brickworks. The works remained derelict when the manufacture of bricks ceased but the last chimney was not blown up until December 1992. The site is now owned and maintained by Milton Keynes Council. The pit from which the Oxford clay was extracted became flooded in the winter of 1946/47, when the normally placid Water Eaton brook burst its banks. The pit is very steep sided, and the water clean, clear and very deep – about 18 metres (60 feet). After the original pit was flooded, a second pit was opened, called the Knot Hole, and when brickmaking ceased this was used for landfill. The remnants of the Knot Hole can still be seen further south in a small lake by the present car park.

Just outside the north-east corner of the reserve is a small lake known as the Newfoundout. Previously used as a water store to fill railway engines in the days of steam, it is now a private fishing lake which can be viewed from a footpath.

What to look for

This is an excellent site with a wide variety of species to be seen at appropriate times of the year.


The more-or-less bare clay of the site probably has the most attractive flowering plants including: Common Spotted-orchidBee OrchidCowslipRagwortsSpotted MedickWhite and Red CampionTansy and Yellow-wort. The margins of the water have Purple LoosestrifeWater MintYellow Iris and the rare Flowering Rush. In the water are Water Crowfoots and Yellow Water-lily.

Numbers of Willow species are present, as well as BlackthornDogwood and Hawthorn in the hedgerows which border most of the site. Brambles are present in abundance – good for their fruits in the autumn!

Well over 200 species of flowering plants, ferns and their allies, including trees, have been recorded.


Commonly seen are FoxGrey SquirrelMuntjac Deer and Rabbit.


Dozens of bird species can be found at different periods of the year and in different habitats. For example, Canada GooseCootGreat Crested GrebeMallard and Mute Swan can be found on the water and ReedSedge and Willow Warblers in the marginal vegetation, whilst various other WarblersTitsFinchesWhitethroats and Woodpeckers occur in the trees and shrubs. Occasionally you may hear the reeling call of the Grasshopper Warbler but it would be a prize day if you actually saw the owner. Similarly, the Cuckoo used to be a regular visitor but has not been heard or seen recently.


Grass Snakes are present and may be seen swimming across the water with just their heads showing.


FrogsToads and Great-crested Newts can be seen in or around the smaller ponds.


The two lakes support a diverse ecosystem where pike, perch and roach are often reported and tench and carp are occasionally seen.


There are crayfish in the lagoon – but take care especially when seeking them, the banks are steep and the water is deep.


This site is one of the best for Damselflies and Dragonflies in the area, with 21 of the species recorded in Milton Keynes being present. Not all can be seen in a single visit because each has its own flight period. The Large Red Damselfly is the first to appear, typically in late April. The first dragonfly (the Hairy Dragonfly) follows in early May. Among the various common damselflies, look especially for males of the Red-eyed Damselfly which can be seen resting on lily pads (easily seen at the Newfoundout) and making territorial flights to search for females or to repel other males. Another species which can be seen but is not known to breed is the Banded Demoiselle that occurs only in small numbers and may be seen by the brook. The wings of the male are a beautiful blue when in flight. Another species, which can be seen by the brook but only then in small numbers, is the Emerald Damselfly, which can be difficult to spot – look for them sitting on stems of emergent plants. Among the dragonflies to be seen are Four-spotted ChaserBlack-tailed Skimmer and Common Darter with Emperors and Brown Hawkers particularly patrolling their territories.

Butterflies are also numerous, with 30 species currently on record, some of which are not commonly seen in Milton Keynes. These include Grizzled and Dingy Skippers,Small BlueCommon BlueWhite-letter HairstreakSmall CopperBrown Argus,Small Heath and Marbled White. Two places on the site which are favourable for butterfly sightings are the large meadow at the north-east corner above the brook and the grassy area in the south-west corner above and left of the small lake (Knot Hole) when viewed from the car park.

Day-flying moths such as Burnet CompanionCinnabar, and Six-spot Burnet are regularly seen.

Self-Guided Walk

Now that you have read about this site why not try one of the Society’s self-guided walks. This link will take you to the walk for the Blue Lagoon and you can find other walks here . You can also view what other people are currently seeing on our Recent Sightings page. Finally, don’t forget to report your sightings to

Blue Lagoon species glossary

The scientific names of all the species mentioned for Blue Lagoon can be found in order of appearance in this species glossary

How to get there

The main entrance is off Drayton Road, to the west of the main railway line, at SP871322 (see OS Explorer map 192 or OS Landranger map 152 or MK City Atlas ref. 13Q). At this point a signpost directs you to under the railway and right into the car park. Here you will find a notice board showing a plan of the site. Most of the paths are made up and level but there are others on grass with the occasional steeper bits. In some places there are well maintained steps and boardwalks across water.

Young children need to be kept under strict control when near boardwalks and along the narrow path close to the southern shore of the lagoon itself (here the water is extremely deep). Most of the site is unsuitable for wheelchairs but a wheelchair user could circle the Knot Hole or get to the east shore of the lagoon (see notice boards).

Access is also possible from a footpath running from the west of a railway bridge in Water Eaton Road which goes alongside the Newfoundout to a stile. To the left, a path leads directly to the centre of the reserve. If this path is not taken, going down the steps will take you alongside and across the brook where to the left you can continue along the path on the western boundary of the reserve bordering the landfill site. By taking any of the smaller paths off to the left you may reach the centre of the site or car park.

For those approaching from Far Bletchley, a path leads from Selbourne Avenue (off Newton Road; SP856331) under the disused railway then left and around the margins of the fields (and landfill site) to a stile on the reserve itself, near the brook.

The nearest public transport

For the main entrance take buses 5 or 5A to the first stop in Fern Grove, walk back to the railway bridge in Drayton Road and then follow the signs to the main entrance/car park.

For the Newfoundout pathway, take buses to Bletchley Bus Station (or Bus 4, alight at the police station) and walk along Water Eaton Road to the railway bridge and then along the path, as above. Bus 4 also stops at the junction of Buckingham Road and Newton Road (by the Three Trees pub) and it is a short walk (100 metres) along Newton Road to reach Selbourne Avenue.

Useful links and further information:

Public Transport

The Parks Trust