Yes, the 2 x FK+1 BG was certainly an odd rake, with only 84 seats (probably insufficient at times), which were obviously charged as second class.
Below are the rakes I observed... the rake numbers given below are my purely arbitrary numbers as I wrote them up at the time, though the letters are obviously the depot I believe they were from, whilst the consecutive numbers represent the order in which they appeared (in some cases, I have stated the date I saw them). Suggest you check a 1989 spotters' book to confirm coach types and liveries... most HT rakes are TP livery (though I think some of the BGs were blue+grey at times), all CL rakes were blue+grey.
HT1 13527 13463 92204 (17/04/1989)
HT2 13527 13532 84010 (29/04/1989)
HT3 5160 5283 5387 5311 92117 (06/05/1989)
HT4 5387 5311 92117 (15/05/1989)
HT5 13463 5160 92250 (08/06/1989)
HT6 13527 13519 92089
HT7 5463 13532 80805
CL8 9462 5413 5288 (07/08/1989)
HT9 5323 13445 92338
HT10 13519 13445 92338
HT11 4366 4785 84210 Mk1 blue+grey rake
HT12 5347 5379 92089
HT13 13527 13445 92089
HT14 13445 13527 92248 (26/08/1989)
HT15 13445 13527 80805 (31/08/1989)
HT16 13445 13527 92351 (02/09/1989)
HT17 4366 4785 84388 (06/09/1989) Mk1 blue+grey rake
HT18 5379 13519 92351 (06/10/1989)
HT19 5343 13519 92351 (09/10/1989)
CL21 5288 5413 9462 (07/11/1989). Also, on 25/11/1989 worked 0630 Newcastle-Seaham and 0726 Seaham-Newcastle behind 31434
CL22 5363 5383 92115 (08/11/1989)
CL23 5363 5144 92115 (11/11/1989)
CL24 5182 5483 92369 (18/11/1989)
CL25 5288 5144 92142 (05/12/1989)
CL26 5288 5144 92369 (28/12/1989)
CL27 5144 5383 92246 (30/12/1989)
CL28 5182 5483 92317 (03/02/1990)
CL29 5282 5383 84388 (10/02/1990)
CL30 5189 5352 5374 92221 (14/07/1990 - 31217 hauling 1500 Middlesbrough-Newcastle, the last loco-hauled I ever saw).