tube-gauge Schoma diesel loco LUL No.4 "PAM" built  for use on the Jubilee line extention project with exhaust and fitted with exhaust scrubber, seen here on a stationary engineering train on the Hammersmith and City line near to Westbourne park tube station
Panhard
CC BY 2.5
<span class="int-own-work" lang="en">Own work</span>