I visited Kersey on May 17th, and the stone by the footbridge isn't any kind of puddingstone. It's what is commonly called 'sparkling sandstone', where quartz grains are enhanced by silica, and the surface sparkles in sunlight. It measures 40cm x 30cm x 25ch high, with its location being TM00057044130.
The slab in the pavement outside No. 2 Ancient Houses is at TL9998244264, and actually IS conglomerate. One edge is broken, showing pebbles that have been sheared clean through, something that typifies classic Hertfordshire puddingstone. It measures 102cm x 72cm x 20cm high at the back.
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