Farmers harvested just 250,000ha (617,500 acres) in the week to Tuesday (30 August), less than half of the usual average, according to the HGCA.
Harvest progress was now on par with normal, although in Scotland it was running late.
“Around 75% of the total combinable crop area is now harvested,” said the report.
“Of the remaining 1m ha (2.5m acres), around half is wheat and one third spring barley, with the majority in the northern regions and Scotland.”
Farmers had cut about 75% of their wheat, with yields marginally below average at 7.5-7.7t/ha (3-3.1t/acre).
“There are some signs that quality of any remaining milling wheat is starting to drop with average Hagberg falling numbers down slightly to 270-280.
“Protein and specific weights are holding at 12-13% and 78-80kg/hl respectively.”
Spring barley harvest was about 55% through, with 25% cut in Scotland and 75% cut in England and Wales, said the report.
Yields were slightly below average at 5.1-5.3t/ha (2-2.1t/acre), although this could change as the Scottish harvest progressed.
“Quality of Scottish samples is good with nitrogen contents of 1.4-1.5%, compared to an average of 1.7-1.9% for English crops.”
Winter oilseed rape harvest was virtually complete, with yields above average at 3.5-3.8 t/ha (1.4-1.5t/acre) and oil contents of 44-46%.
Farmers had cut about 20% of the spring rapeseed crop, with yields at about 2t/ha (0.8t/acre).
Oats were about 70% cut, with average yields of 5.7t/ha (2.3t/acre) and bushelweights of 50-52kg/hl, it added.
Winter barley harvest was complete, with yields 5% below average at 6-6.2t/ha (2.4-2.5t/acre) and nitrogen contents above normal at 1.4-2%.