Mr Green explains why here. Previously the definitions were available to all, but the examples required a subscription. Now you can see the examples too.
For example, a Norfolk breakfast is no breakfast at all:
1939 Beds Times 25 Aug. 6/2: In the eastern Counties they galk [talk?] about giving the pigs a ‘Norfolk breakfast’ on Sunday mornings — which means they get no breakfast.
Many of the terms are, of course, unsuitable for polite company.
The three volumes of the 2010 print edition can be consulted in UEA Library.