I found this egg sack today which belongs to the Wasp spider, a new comer to the UK and one which hasn’t to my knowledge been recorded at Cavenham Heath NR
The Wasp Spider is a very large, colourful spider that is a recent arrival in the UK from the continent and has slowly spread over the south of England. They build large orb webs in grassland and heathland, and attach their silk egg-sacs to the grasses. The web has a wide, white zig-zag strip running down the middle, known as a ‘stabilimentum’, the function of which is unclear. Mating is a dangerous game for males; they wait at the edge of the web until the female has moulted into a mature form, then take advantage of her jaws being soft and rush in to mate. However, many males still get eaten during this time.
(spider Photo not mine)