Although the coprolite diggings started in the area around Felixstow in about 1845 there has been no evidence of the work extending into the parishes of Trimley St. Martin or Trimley St. Mary until the 1880s. There had been men employed as stone dredgers, going out into the estuary to dredge septaria, nodules of clay, which was used in the manufacture of Roman Cement but the phosphatic nodules would probably have been exposed in crag pits in a seam between the overlying Red Crag and the London Clay. No documentation has emerged to show they were exploited by local landowners but the earliest reference to the diggings in this area was in the early 1870s when a number of coprolite pits were reported as in operation. A geological account of the area referred to a newly opened coprolite working in 1874, "at the top end of the little wood about a mile northwest of Trimley churches, and close to the railway." The overlying Crag was from four to six feet thick and as the phosphate bed was up to three feet thick it would have been a very profitable venture, especially being so close to the railway. The same seam was also worked in a pit, "at the back of a cottage about three quarters of a mile westnorthwest of the churches," and also just to the northeast and southeast but it was only six inches thick here below cover of up to seven feet.
The 18.. map of the area showed a number of crag pits, the largest being Hanging Crag Pit just east of Loompit Grove. "Round Grimston Hall, half a mile west of Trimley, coprolites have been largely worked," yet in 1874 there were four workings in which the seam was exposed. The first, between seven and nine feet deep was just southwest of the house, the second, up to sixteen feet deep, was, "a little north of the farm, on the western side of the lane to Trimley." A third, six feet deep, was on the opposite side of the lane and a little to the south and the fourth "in full work," just northeast of the Farm was about twenty two feet deep. A little to the southeast close to Fagbury Cliff the bed was worked again. (Whitaker, "Geology of Ipswich Etc." 1885,pp.52-3)
Interestingly, when the 25" map was first published in 1881 there were still two "coprolite pits" in operation in Trimley St. Martin a quarter of a mile north of Aleston Hall at the end of Common Lane. (25" 1881 map 83.15) There were also two more crag pits near Milford Cottage half a mile east northeast of Trimley. As no records of agreements have come to light there is the strong possibility the landowner at the time arranged for them to be raised and sold them to the manure manufacturers.
The 1881 census revealed that there were only five men involved, all locals living on Lower Street, Trimley St. Martin, with Daniel Brown the eldest at 40 and Henry Collins the youngest at 22. Their average age was 31, showing that it tended to be the work of older men, as many of the younger men during the period of the agricultural depression had left the countryside to find work in the towns. However, according the to the trade directory for 1885 it was,
"a department of industry which is now employing a good deal of capital as well as labour... There are extensive beds of coprolites in Suffolk, chiefly at Kirton, Trimley, Felixstowe, Bawdsey, Alderton and other places in the Colneis and Witchford Hundreds... Immense quantities are raised in Colnei Hundred. Whole fields have been regularly turned over, sometimes to the depth of 30 or 40 feet. It is usually undertaken by the tenant, who pays a royalty to the landlord of so much per ton. The work is carried on with more or less vigour, according to the season when labour is scarce or plentiful. The surface soil is carefully preserved at top, so that the land from which the coprolite has been taken is not materially damaged. The tenant sells and carts to the nearest town or wharf at such times as his horses are most at liberty. The depression in agriculture has caused a corresponding slackness in the manufacture of artificial manures and the raw material which the coprolite furnishes has not now a very ready sale."
See Berridge Eve’s account of Trimley St Martin and the Coprolite Mining Rush