Another really good day's digging today in Forty Hall, on day four of our two-week search for the remains of the inner gatehouse of Henry VIII's Elsyng Palace.

Yesterday afternoon, after opening a fourth trench on the ostensibly man-made mound in the woods to the west of the Hall's lime tree avenue, we uncovered a very shallowly buried and quite skinny Tudor wall, which ran at an angle across part of the trench and seemed to thicken as it entered the section of the trench's north west corner.

The first task of this morning, then, was to extend Trench 4 at that north corner to reveal more of the wall and to continue excavation either side of it to try and determine whether each side showed evidence of being an interior or exterior surface.

The wall seemed too thin to be substantially structural, and so we assumed it was either part an interior partition wall or a relatively small free standing structure, perhaps even something like a garden wall.

On extending the trench, we were very pleased to find that not only does the wall thicken quite substantially, but it also includes a right angled turn to the east, with a decorative octagonal shape on the outside corner, and what looks like the beginnings of a brick floor on the inside.

Although these walls may still not be wide enough to support the four-story gatehouse we are looking for, they do represent a brand new unidentified palace building, and having found a corner we were keen to follow the new direction of the wall east to see if we could begin to define the building's footprint.

We therefore opened Trench 5, a small trench located a couple of metres east on the line of the east return of the new wall, to try and pick up more of it in that direction.

Before long, however, this trench began to turn up large amounts of rubble and eventually a very concentrated deposit of crushed brick dust, in contrast to the trench with the wall in it, which had relatively little rubble and loosely packed pebbles next to the walls (apart from the brick floor).

The crushed brick peeled off to reveal a concentrated and very flat layer of pebbles with occasional patches of mortar - potentially an interior floor surface - and no sign of the eastern continuation of the wall from Trench 4.

Where the east return of the wall meets the east section of Trench 4, it becomes very ragged and it may be that the wall line in this direction has been cut off and truncated where it once crossed Trench 5.

It looks likely, then, that one of tomorrow's first jobs will be to begin to excavate the ground between Trenches 4 and 5 to find out what goes on between them. The pebbles in Trench 4, in contrast to those in Trench 5, do not look deliberately lain, and so we will probably begin to remove them tomorrow, which will hopefully begin to give us an idea of how many courses of brickwork survive. At some point we may also extend Trench 4 northwards to uncover more of the brick floor.

There is still much more work to do, but fortunately we still have plenty of time.