<p>GB Railfreight's class 66/7 (JT42CWR) number 66740. Here it is photographed hauling empty gypsum containers mounted on flat wagons from Mountfield Sidings (GBRf) East Sussex to Doncaster Down Decoy (4E19) on 9 February 2015. To comply with gas emission regulations limestone (CaCO3) delivered to the power station (by other trains) is used to remove sulfur dioxide (SO2) from the flue gasses, by converting it into gypsum (CaSO4·2H2O). The waste product (gypsum) is then delivered to British Gypsum's Robertsbridge Works by train where it is used to manufacture plaster and plasterboard.  
</p><p>According to Realtime Trains the route and timings were;
Mountfield Sidings [XMX]....1130..........................1216..........................46L
Mountfield Tunnel.................1132..........................1218..........................46L
Robertsbridge [RBR].............1134 1/2....................1224 1/2..................50L
Wadhurst [WAD]....................1147...........................1236 1/2..................49L
Tunbridge Wells [TBW] 1.....1156/1158.................1247 1/4/1250 1/4..52L
Tonbridge [TON] UF.............1215..........................1300.........................45L
Sevenoaks [SEV] 1.................1225.........................1311...........................46L
Chelsfield [CLD].....................1231 1/2....................1320 1/2..................48L
Orpington [ORP] 2.................1233.........................1322.........................49L
Petts Wood Junction............1234 1/2...................1324 3/4..................50L
Bickley Junction[XLY]..........1252.........................1325 1/2..................33L
Bromley South [BMS]...........1257.........................1327 3/4..................30L
Shortlands [SRT]....................1300.........................1328 3/4..................28L
Shortlands Junction..............1301..........................1332..........................31L
Bellingham [BGM].................1304 1/2...................1335 1/2....................31L
Nunhead [NHD] 1...................1308.........................1342 1/2...................34L
Peckham Rye [PMR] 3..........1309 1/2...................1344 3/4..................35L
Crofton Road Junction.........1310 1/2....................1347 1/4...................36L
Denmark Hill [DMK] 1............1311 1/2.....................1348.........................36L
Voltaire Road Junction........1317...........................1352.........................35L
Clapham Junction [CLJ] 5...1330 1/2...................1359.........................28L
Wandsworth Town 2............1332 1/2...................1403 1/4...................30L
Putney [PUT] 3.......................1335.........................1406 1/2...................31L
Barnes [BNS] 3.......................1337 1/2...................1409 1/2..................32L
Barnes Bridge [BNI] 2...........1339 1/2...................1411 3/4....................32L
Chiswick [CHK] 2...................1342.........................1413 1/4.....................31L
New Kew Junction................1344 1/2...................1418 1/2....................34L
Kew East Junction................1347 1/2...................1419 1/2...................32L
Acton Central [ACC].............1355.........................1427..........................31L
Acton Wells Junction...........1357 1/2...................1431 1/2....................34L
Willesden Junction 4............1359 1/2/1401 1/2...1434 1/4/1436 1/2..35L
Kensal Green Junction........1403 1/2...................1438 3/4..................35L
Brondesbury Park [BSP] 1....1407..........................1441..........................34L
West Hampstead 2...............1409 1/2...................1443.........................33L
Hampstead Heath 2.............1413...........................1445 1/2..................32L
Gospel Oak [GPO].................1415..........................1447 1/4...................32L
Alexandra Palace [AAP] 3...1443 1/2...................1501 1/2....................18L
New Southgate [NSG] 4......1446.........................1504 1/2...................18L
Oakleigh Park [OKL] 4..........1450.........................1508 1/2...................18L
New Barnet [NBA] 4..............1451 1/2....................1510 1/2....................19L
Hadley Wood [HDW] 4.........1454.........................1513 1/4.....................19L
Potters Bar [PBR] 4................1458.........................1517...........................19L
Brookmans Park [BPK] 4......1501..........................1520 1/2...................19L
Welham Green [WMG] 2......1503.........................1523 3/4..................20L
Hatfield [HAT] 3.....................1507.........................1527 1/2...................20L
Welwyn Garden City 3.........1511 1/2.....................1530 3/4..................19L
Welwyn North [WLW] 2........1526 1/2...................1532 3/4.....................6L
Woolmer Green Junction....1529.........................1534 3/4.....................5L
Knebworth [KBW] 4...............1530.........................1536 1/4......................6L
Stevenage [SVG] 4................1532 1/2...................1538 3/4.....................6L
Hitchin [HIT] 2........................1540 1/2...................1542 3/4.....................2L
Arlesey [ARL] 2......................1544 1/2...................1547 3/4.....................3L
Biggleswade [BIW] 4............1548.........................1551 3/4......................3L
Sandy [SDY] 2........................1550 1/2...................1554 1/4.....................3L
St Neots [SNO] 1....................1556 1/2...................1601.............................4L
Huntingdon [HUN] 3.............1602 1/2...................1607 3/4.....................5L
Holme Junction [XHO].........1611 1/2.....................1619 1/4......................7L
Fletton Junction.....................1617 1/2....................1627............................9L
Peterborough [PBO] 4.........1620 1/2/1632 1/2..1631 1/2/1634 1/4.......1L
Helpston Junction.................1640.........................1642............................2L
Tallington Junction...............1644 1/2...................1646 3/4.....................2L
Stoke Junction.......................1702/1710................NoRep/1711 3/4.........1L
Grantham [GRA] 2.................1716 1/2....................1718 3/4......................2L
Claypole Loop........................1725.........................1726 1/4.......................1L
Newark North Gate 1............1729 1/2/1734 1/2...1732 1/4/1732...........2E
Newark Crossing East Jn....1737..........................1735 1/2......................1E
Gainsborough Lea Road ....1819..........................1814............................5E
Gainsborough Trent Jn........1827 1/2...................1815...........................12E
Bessacarr Junction...............1849 1/2...................1834..........................15E
</p>
Doncaster Down Decoy......1854.........................1839..........................15E
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<a rel="nofollow" class="external text" href="https://www.flickr.com/photos/99279135@N05/16481817512/">66740 Mountfield to Doncaster Down Decoy 4E19</a>