3 – 1 2 0 4 2 ▁: ▁British ▁Rail ▁Class ▁D 3 / 8 ▁( L ater ▁T OP S ▁Class ▁ 1 1 ), ▁tw in ▁motor ▁ ▁N B : ▁Production ▁of ▁the ▁last - ment ioned ▁class ▁continued ▁after ▁National isation , ▁with ▁the ▁following ▁two ▁locomot ives ▁emer ging ▁as ▁M 7 1 3 0 ▁and ▁M 7 1 3 1 ▁( l ater ▁ 1 2 0 4 3 / 1 2 0 4 4 ) ▁and ▁the ▁remainder ▁carrying ▁BR ▁numbers ▁ 1 2 0 4 5 – 1 2 1 3 8 ▁from ▁new . ▁Although ▁allocated ▁T OP S ▁Class ▁ 1 1 , ▁none ▁of ▁these ▁locomot ives ▁were ▁ren umber ed . ▁When ▁ 1 2 0 8 2 ▁was ▁re - register ed ▁for ▁use ▁on ▁the ▁main line , ▁it ▁was ▁allocated ▁T OP S ▁number ▁ 0 1 5 5 3 ▁in ▁the ▁ex - indust rial ▁registered ▁sh un ters ▁list . ▁ ▁Department al ▁ 5 5 1 9 ▁/ ▁Z M 9 ▁ ▁Department al ▁ 2 ▁/ ▁ED 1 ▁This ▁locomot ive ▁was ▁very ▁similar ▁to ▁the ▁Great ▁Western ▁Railway ' s ▁dies el ▁locomot ive ▁number ▁ 1 . ▁ ▁Un number ed ▁plant ▁locomot ives ▁ ▁Tri al ▁locomot ives ▁The ▁L MS ▁used ▁a ▁number ▁of ▁locomot ives ▁on ▁loan ▁from ▁their ▁manufact ur ers ▁for ▁tri als . ▁These ▁locomot ives ▁were ▁not ▁allocated ▁L MS ▁numbers , ▁and ▁details ▁of