Piecing together from postings elsewhere, it appears that they potentially work the following
5B04 0422 Orient Way Cs to London Liverpool Street
1B04 0506 London Liverpool Street to Stansted Airport
1B05 0615 Stansted Airport to London Liverpool Street
1B24 0740 London Liverpool Street to Stansted Airport
1B25 0842 Stansted Airport to London Liverpool Street
1B44 1010 London Liverpool Street to Stansted Airport
1B45 1112 Stansted Airport to London Liverpool Street
1B64 1240 London Liverpool Street to Stansted Airport
1B65 1342 Stansted Airport to London Liverpool Street
1B84 1510 London Liverpool Street to Stansted Airport
1B85 1612 Stansted Airport to London Liverpool Street
1B04 1739 London Liverpool Street to Stansted Airport
1B05 1842 Stansted Airport to London Liverpool Street
1B24 2010 London Liverpool Street to Stansted Airport
1B25 2112 Stansted Airport to London Liverpool Street
1B44 2240 London Liverpool Street to Stansted Airport
1B45 2342 Stansted Airport to London Liverpool Street
5M64 0100 London Liverpool Street to Orient Way Cs
5B20 0550 Orient Way Cs to London Liverpool Street
1B20 0710 London Liverpool Street to Stansted Airport
1B21 0812 Stansted Airport to London Liverpool Street
1B40 0940 London Liverpool Street to Stansted Airport
1B41 1042 Stansted Airport to London Liverpool Street
1B60 1210 London Liverpool Street to Stansted Airport
1B61 1312 Stansted Airport to London Liverpool Street
1B80 1440 London Liverpool Street to Stansted Airport
1B81 1543 Stansted Airport to London Liverpool Street
1B00 1709 London Liverpool Street to Stansted Airport
1B01 1812 Stansted Airport to London Liverpool Street
1B20 1940 London Liverpool Street to Stansted Airport
1B21 2042 Stansted Airport to London Liverpool Street
1B40 2210 London Liverpool Street to Stansted Airport
1B41 2312 Stansted Airport to London Liverpool Street
5M54 0015 London Liverpool Street to Orient Way Cs
Note however that there was a swap at Liverpool Street between a Norwich and Stansted working between 1B25 and 1B44 today. Also, there were failures. I suggest that a check is made of Greater Anglia journey check
https://www.journeycheck.com/greateranglia/ for services formed of 12-cars with no first class. 1B41 and 1B45 are both shown as having had first class reinstated.