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English Church Architecture.


BOURN, St. Helen & St. Mary  (TL 324 564),


(Bedrock:  Lower Cretaceous, Gault.)


A large and important church situated on the Lower Greensand outcrop,

built largely of ironstone.




Before the advent of the canals and (especially) the railways, the transport of heavy goods overland frequently cost more than the goods did themselves.  Builders, therefore, used vernacular materials whenever possible, preferably sourced within a mile or two of the site.  Mediaeval stone buildings consequently reflect the underlying geology and churches in particular provide an approximate geological map of Britain, which is naturally most faithful in areas of less complexity.   This general principle is revealed to good effect along the Lower Greensand ridge which rises along the western edge of the Lower Cretaceous outcrop of south and east England, which is itself very narrow in the southeast/northwest direction, yet extensive and continuous from northeast to southwest, as seen below.   Moreover, the rubble building stones to which the Lower Greensand gives rise, which are generally known as carstone (chiefly in Norfolk) or  ironstone,  are a very distinctive, liquorice-brown colour, which is difficult to miss.  Drivers heading northwest from East Anglia to the Midlands along one of the quieter roads that passes through intermediate villages, will suddenly notice one or two village churches (probably no more) that show they are crossing this outcrop, while someone with a will to do so, might set out from Hunstanton on the north Norfolk coast and, except across the Fens, pick his or her way southwest, at least as far as Leighton Buzzard on the southern border of Bedfordshire, and encounter one such church after another.  The churches named on the map below, all of which are represented on this web-site, serve to illustrate this.





The Lower Cretaceous Rocks of Eastern England, laid down 146-97 Ma.


1 = Heacham (Norfolk);  2 = Castle Rising (Norfolk);  3 = Wilburton (Cambridgeshire);    4 = Cottenham (Cambridgeshire);  
5 = Great Gransden (Cambridgeshire);  6 = Bourn (Cambridgeshire);   7 = Gamlingay (Cambridgeshire); 
8 = Everton (CENTRAL Bedfordshire);  9 = Blunham (CENTRAL Bedfordshire);   10 = Eyeworth (CENTRAL Bedfordshire);  
11 = Biggleswade (CENTRAL Bedfordshire);   12 = Edworth (CENTRAL Bedfordshire); 


The valley of the Bourn Brook, in which is now situated the growing modern development of Cambourne beside the recently-duelled A428, was an area of major settlement at least as far back as Roman times, and this is reflected in the cluster of ancient villages that shelter in it, in the lee of the low, clay plateau to the north, west and south.  Bourn itself is one of the largest of these villages, and it has undoubtedly the most important parish church, with a large Norman-Transitional aisled nave and an especially fine, albeit rather broad and short, Early English W. tower.  The building is pseudo-cruciform in plan (i.e. it has transepts but no true crossing) with the addition of nave aisles.  It is constructed of ironstone rubble and pebbles, with limestone dressings.


The best part of the building is the tower, which rises in three stages to battlements and a lead-covered spire that can compete for crookedness with Chesterfield in Derbyshire or Cleobury Mortimer in Shropshire.  The stair turret projecting above the battlements at the southwest angle, is a Perpendicular addition, but the bell-openings formed of pairs of transomed lancets set in the central arches of three-bay blank arcades with bays divided by semi-octagonal shafts with capitals, are clearly of early thirteenth century date.  The W. window (shown below) has two lights and plate tracery, which is particularly helpful in dating the work since plate tracery was rarely used after c. 1245, while the W. doorway beneath is particularly impressive, with six orders of colonnettes and an arch of complex profile formed of rolls with fillets.  Internally, the great arch to the nave is composed of three flat-chamfered orders springing from responds formed of five shafts, and there are similar, albeit slightly smaller arches to the north and south, showing the aisles were extended to the westwards alongside the tower when the tower was first built, and this is confirmed by the lancets in the aisle W. walls, set between smaller blank arches of two orders.

However, the nave and five-bay nave arcades predate this work by possibly half a century, being composed of tall, double-flat-chamfered pointed arches supported on alternately circular and octagonal piers with plain capitals to the north and scalloped capitals to the south (as illustrated left and below right respectively), suggesting, perhaps, that the S. arcade was built first.   A further arch leads from the S. aisle to the S. transept, but there is no equivalent arch to the north.   The chancel arch, balanced precariously on corbels, dates from a Victorian restoration.


The aisle and chancel windows adopt an assortment of Decorated and Perpendicular forms and are heavily restored.  The S. transept is lit from the east by a two-light window with curvilinear tracery and, further to the right (as viewed from within), a second with a straightened reticulation unit in the head, which is probably a late fourteenth century insertion.  The N. transept has a two-light E. window with reticulated tracery, commensurate with c. 1340, and the N. aisle windows are three-light and untraceried.  However the clerestory windows are more interesting for they comprise five pairs of quatrefoils in circles which are probably contemporary with the arcades. The inner doorway, inside the porch, is late Norman work of c. 1190:  the arch is round-headed and composed of two orders, with narrow shafts either side.


Carpentry in the church includes, first and foremost, the hammerbeam roof above the chancel, where the purlins and principal rafters are mediaeval although the angels are not.  The rood screen is probably early sixteenth century in date and  constructed of five sections with ogee arches, supermullioned tracery and a castellated supertransom, while the fine manorial pew immediately to the southwest, has characteristic Jacobean, blank round arches decorating the sides.  The choir stalls and nave benches are partly old and there are a lot of them, but it is difficult to distinguish between the original work and the new.  Pevsner recorded the date '1537' on one of the former, not noticed by this writer.