What is the Oxford to Cambridge Arc?

The Oxford to Cambridge Arc is a government-led, large-scale ‘growth corridor’ to connect the two cities and principal towns in between.

The government believes this will be for connectivity and economic growth.

The proposed plans suggest road and rail links and the development of a million houses.

What has happened so far?

There are various projects at various stages. The latest on the three plans are:

  • Road: As it currently stands, the plans for this major road project, known as the Oxford-Cambridge Expressway, have now been postponed to explore several smaller road links following In 2018, opposition from local organisations.
  • Housing: local plans to build these have allotted, and some houses are already under construction. Government funding has been allocated to accelerate 100,000 new homes in the area before 2031.
  • Rail: Known as the East-West Railway, the rail project will be built in three sections. The Western ‘Phase One’ between Oxford and Bicester was completed in 2016. The Western ‘Phase Two’ between Bicester and Bedford began reconstruction and upgrades at the start of 2020. There is still ‘consultation work’ to find the preferred route of Eastern ‘Phase 3’ between Bedford and Cambridge. A second non-statutory consultation will be held in early 2021.  

What impact does this have on wildlife and CRT Westfield?

We have been monitoring the routes suggested by the East-West Railway project. The latest preferred route option is potentially disastrous for nature and wildlife habitats in the Cambridge area.

The rail link's proposed route will directly and negatively impact wildlife habitats and species numbers and divide habitat corridors throughout the area. The route could destroy 27 years of endeavour to increase national declining species on CRT land at Westfield Farm in Comberton.

We have been approached to have environmental studies on our land at Westfield Farm, Comberton, in 2021. The East-West Railway project has recently released an interactive map showing the route in a blue-grey proposed area (and layers of land designation can be highlighted).

Westfield lies south-west of Comberton, and despite being listed as a ‘Priority Habitat’ (by Natural England) and a Greenbelt area (by The Ministry of Housing, Communities and Local Government's formerly the Department for Communities and Local Government) which is specially designated area of countryside protected from most forms of development, the route dissects through the land.

The concern is that this devastates CRT land and other habitats, reserves, and local homes.  We join other organisations suggestions that the railway line should follow the A428 and not obliterate the precious rural countryside to the west of Cambridgeshire.

Westfield Wildlife – protected species, rare species, and abundance of farmland species

We are extremely concerned about the impact the East-West Railway project will have on the habitats of protected, rare and farmland species. These include many BAP species identified as being the most threatened and requiring conservation action under the UK Biodiversity Action Plan (UK BAP).

Skylark In Stubble © John MurrayBirds

  • Yellowhammer (in the top 1% of sites nationally 2019)
  • Grey partridge (in top 1% of sites nationally 2019)
  • Corn Bunting (numbers in the top 10% of sites nationally 2019)
  • Skylarks (numbers in the top 10% of sites nationally 2019)
  • Linnet
  • Song Thrush
  • Barn Owl
  • Kingfisher
  • Starlings
  • Hobby (rare migratory falcon – spotted 2020)
  • Lapwings (winter visitor)
  • Golden Plover (winter visitor)

Winter bird counts at Westfield also show the site's importance, where our farmer leaves many stubble fields and patches of seed-bearing crops for birds.

  • The numbers have gone up 7-fold since we first started farming this land in 2002, with large counts of Yellowhammer, in particular, moving from about 5 in 2002 to over 75 in 2019.
  • Large numbers of Linnets, Skylarks and Grey Partridges are a regular feature of the farm in winter, and there are also visits from Lapwings and Golden Plovers.


Large numbers of brown hares on-site, with double-figure counts, regularly seen. Brown Hares are listed as a Priority Species under the UK Post-2010 Biodiversity Framework.

At least one Badger sett with activity in other areas suggesting possibly a secondary sett developing. It is against the law, under the Protection of Badgers Act 1992, in England and Wales to disturb a badger and intentionally or recklessly damage or destroy a badger sett or obstruct access to it.

Bats are not systematically recorded but are seen Pipistrelles particularly. Also, there are recorded sightings of the Barbastelle bat.

In 2020 we undertook our first Harvest Mouse nest exploration on Westfield and found a nest, demonstrating that this species is present on site.

Bourn Brook through Westfield

The Bourn Brook's riparian habitat that runs through Westfield is regularly monitored and maintained to create habitats for declining species and remove invasive species.

Water Voles have colonised the site following work on the Bourn Brook to remove the invasive American Mink. Through a collaborative project, started in 2011, called the Bourn Free project, the local numbers of Water Vole has risen on other parts of the Bourn Brook that flows through Lark Rise Farm, CRT land in Barton.

Otters are known to be regular visitors to the site in Westfield. Although classified as a species of Least Concern in England, on a global scale, this species is Near Threatened.

Westfield was the site where the first live-sighting of a wild, native Polecat was made in Cambridgeshire when one entered one of our mink traps and was released back into the wild following photographs as a record of the sighting.


Grass snakeGrass snakes are seen in most years, including one record in 2020. These reptiles are listed as a Priority Species under the UK Post-2010 Biodiversity Framework.

Great Crested Newts have been recorded on a few occasions. Great Crested Newts are listed as a Priority Species under the UK Post-2010 Biodiversity Framework.

Common newts, Common frogs and Common toads are all regularly present.


There is a regular survey of butterflies on the site, with nearly 20 years of data fed into the national butterfly monitoring scheme. This long-running data set would be threatened if a railway line crosses the site.

Purple hairstreak
While most species recorded are common and widespread, we have a good assemblage of species, including Small Coppers, Marbled Whites and Purple Hairstreaks.

In recent years, the Biodiversity Action Plan Species White-letter Hairstreak has been recorded with photographic evidence.


Many rare and scarce arable weeds have been recorded on Westfield.

An example of some of the arable weeds include:

  • Shepherd’s Needle
  • Sharp-leaved Fluellens
  • Night-flowering Catchfly

Restored hay-meadows now have naturally colonised by Pyramidal Orchids recorded among other species.

Methods of Survey

We use two survey methods for recording bird species – Red List Revival ‘snapshot’ and Common Birds Census counts of territories.

Westfield ranked highly by Red List Revival (RLR) comparative studies.

Using the same 2 x 1km transect technique applied to random 1km grid squares across the UK, we see above-average numbers of many Red-listed farmland birds (Species of Conservation Concern).

Common Bird Census (CBC)

Common Bird Census (CBC) monitoring of birds on the Westfield farmland shows the total number of territories (as opposed to the number of birds counted on each of two ‘snapshot’ visits in the RLR method).

CBC results for 2020 are still being compiled, but the 2019 data show the following number of territories of Red-listed species:

Species Territories:

4 Grey Partridge

18 Skylark

6 Song Thrush 

5 Linnet        

11 Yellowhammer 

Other species recorded include Barn Owl, which regularly breeds in nest boxes and Kingfisher, which feed and nest along the Bourn Brook. In 2020 the survey detected nesting Starlings and the rare migratory falcon, the Hobby.