Had to do a revisited here and the owners have now cleared all the undergrwth and bushes from the site The entrance to the tower pillbox is now visible at the side,not through the roof as I previously thought.I'll repost the whole thing this time along with this piece from Norfolk heritages site.
"The surviving north transept of Bromholm Priory was utilised as a converted strongpoint. The existing medieval structure was reinforced internally with concrete with loopholes placed on all sides.The pedestal of a spigot mortar is located immediately to the east of the strongpoint.It is probable that this is the spigot mortar emplacement visible on 1946 aerial photographs.A second spigot mortar pedestal is located on the northern edge of the field at TG 3481 3332. This spigot mortar emplacement was not visible on any aerial photographs. Part of an L-shaped section post survives at TG 3466 3324 built into a boundary wall. This structure was not clearly visible on World War Two aerial photographs. A type 22 pillbox is located at TG 34648 33154. This pillbox has unusual flint facing to disguise it as part of an old wall. It is visible on 1946 and later aerial photographs. A possible spigot mortar pedestal is visible immediately to the north of this pillbox on 1980s aerial photographs. It was not recorded by the Norfolk Defensive Structures Survey in 1994 and may not have still been in position at that time. A spigot mortar pedestal was identified approximately 30m further to the northeast, in the garden just west of the tennis court. No pedestal was visible at that location on the 1980s aerial photographs and it is possible that this was the same pedestal that had been moved between these two dates.
World War Two aerial photographs show that the priory was surrounded by a barbed wire perimeter in 1943. A curving line of barbed wire defences extended from TG 34610 33300 to TG 34740 32940 aligned roughly parallel to the southwest boundary of the field. Further barbed wire defences were present between TG 34579 33314 and TG 34679 33290, TG 34633 33028 and TG 34681 33131, and TG 34762 33344 and TG 34753 33231. Shorter lengths of barbed wire were also located at TG 34564 33179 and TG 34724 33158. Possible weapons pits are visible at TG 34705 33176 and TG 34760 33263. The poor quality of the 1943 aerial photographs and the presence of farm buildings and associated structures makes the identification of World War Two features at this site difficult."
The strongpoint pillbox is closed off in the centre with the only access to this middle chamber being through a hatch in the roof which leads to "underground rooms and passages" presumably from the original priory construction ? This is sealed now with a concrete slab.
Rear view showing hatch on top
E01599 (3) by Rich Cooper2012, on Flickr
E01599 (22) by Rich Cooper2012, on Flickr
E01599 (23) by Rich Cooper2012, on Flickr
Inside
E01599 (24) by Rich Cooper2012, on Flickr
E01599 (26) by Rich Cooper2012, on Flickr
E01599 (27) by Rich Cooper2012, on Flickr
E01599 (30) by Rich Cooper2012, on Flickr
E01599 (35) by Rich Cooper2012, on Flickr
E01599 (39) by Rich Cooper2012, on Flickr
E01599 (41) by Rich Cooper2012, on Flickr
Back outside
E01599 (12) by Rich Cooper2012, on Flickr
E01599 (11) by Rich Cooper2012, on Flickr
E01599 (7) by Rich Cooper2012, on Flickr
First of the 3 Spigots
E23606 (1) by Rich Cooper2012, on Flickr
Nearby another
A by Rich Cooper2012, on Flickr
And the 3rd which is out of situ now
E 23607 (1) by Rich Cooper2012, on Flickr
There are remains of what was a section post next to the farmhouse
E01284 (1) by Rich Cooper2012, on Flickr
And the flint camo'd type 22 to the rear of the garden
E23442 (1) by Rich Cooper2012, on Flickr
E23442 (3) by Rich Cooper2012, on Flickr
E23442 (6) by Rich Cooper2012, on Flickr
"The surviving north transept of Bromholm Priory was utilised as a converted strongpoint. The existing medieval structure was reinforced internally with concrete with loopholes placed on all sides.The pedestal of a spigot mortar is located immediately to the east of the strongpoint.It is probable that this is the spigot mortar emplacement visible on 1946 aerial photographs.A second spigot mortar pedestal is located on the northern edge of the field at TG 3481 3332. This spigot mortar emplacement was not visible on any aerial photographs. Part of an L-shaped section post survives at TG 3466 3324 built into a boundary wall. This structure was not clearly visible on World War Two aerial photographs. A type 22 pillbox is located at TG 34648 33154. This pillbox has unusual flint facing to disguise it as part of an old wall. It is visible on 1946 and later aerial photographs. A possible spigot mortar pedestal is visible immediately to the north of this pillbox on 1980s aerial photographs. It was not recorded by the Norfolk Defensive Structures Survey in 1994 and may not have still been in position at that time. A spigot mortar pedestal was identified approximately 30m further to the northeast, in the garden just west of the tennis court. No pedestal was visible at that location on the 1980s aerial photographs and it is possible that this was the same pedestal that had been moved between these two dates.
World War Two aerial photographs show that the priory was surrounded by a barbed wire perimeter in 1943. A curving line of barbed wire defences extended from TG 34610 33300 to TG 34740 32940 aligned roughly parallel to the southwest boundary of the field. Further barbed wire defences were present between TG 34579 33314 and TG 34679 33290, TG 34633 33028 and TG 34681 33131, and TG 34762 33344 and TG 34753 33231. Shorter lengths of barbed wire were also located at TG 34564 33179 and TG 34724 33158. Possible weapons pits are visible at TG 34705 33176 and TG 34760 33263. The poor quality of the 1943 aerial photographs and the presence of farm buildings and associated structures makes the identification of World War Two features at this site difficult."
The strongpoint pillbox is closed off in the centre with the only access to this middle chamber being through a hatch in the roof which leads to "underground rooms and passages" presumably from the original priory construction ? This is sealed now with a concrete slab.
Rear view showing hatch on top
E01599 (3) by Rich Cooper2012, on Flickr
E01599 (22) by Rich Cooper2012, on Flickr
E01599 (23) by Rich Cooper2012, on Flickr
Inside
E01599 (24) by Rich Cooper2012, on Flickr
E01599 (26) by Rich Cooper2012, on Flickr
E01599 (27) by Rich Cooper2012, on Flickr
E01599 (30) by Rich Cooper2012, on Flickr
E01599 (35) by Rich Cooper2012, on Flickr
E01599 (39) by Rich Cooper2012, on Flickr
E01599 (41) by Rich Cooper2012, on Flickr
Back outside
E01599 (12) by Rich Cooper2012, on Flickr
E01599 (11) by Rich Cooper2012, on Flickr
E01599 (7) by Rich Cooper2012, on Flickr
First of the 3 Spigots
E23606 (1) by Rich Cooper2012, on Flickr
Nearby another
A by Rich Cooper2012, on Flickr
And the 3rd which is out of situ now
E 23607 (1) by Rich Cooper2012, on Flickr
There are remains of what was a section post next to the farmhouse
E01284 (1) by Rich Cooper2012, on Flickr
And the flint camo'd type 22 to the rear of the garden
E23442 (1) by Rich Cooper2012, on Flickr
E23442 (3) by Rich Cooper2012, on Flickr
E23442 (6) by Rich Cooper2012, on Flickr