Lob corpus; British English; 1961; written
Brown corpus; American English;1961;written
Flob corpus; BrE;1991; written
Frown Corpus; AmE;1992;written
Each corpus contains a million words, in 500 text samples from 15 different genres. The four corpora are built according to the same design and sampling method.
Frankly speaking, LOCNESS is much thinner than CLEC. However, the difference in size between learner corpus and native-speaker corpus should not be a hindrance to research.