Did the Pendleton / Brindle Heath Binliners need to run to Burnden Jn / Bolton to run round and reverse before heading for the Calder Valley or Standedge lines?
No, they were able to run round in the loop at Brindle Heath and depart towards Manchester. In the late 90s the only freight I can imagine using the loops at Burnden might have been engineering trains. During the West Coast Route Modernisation project (late 90s / early 2000s) I have vague memories of some weekends when engineers trains ran from Crewe via Manchester and Bolton to Preston, to divert around other possessions on the WCML. 56s would have been fairly common on possession trains in the area around this time.
One possibility is the siding around Westhoughton: was that then still in use?
After some delving, I'm surprised to find that this siding was in use in the late 90s. Although rail deliveries of tinplate to Westhoughton (from Ebbw Vale and Trostre) had ceased in the early 90s, they resumed during the EWS "Enterprise" era of the late 90s. In Paul Shannon's book
Wagonload Freight Since 1968 Westhoughton is shown as part of the 1999 Enterprise network, and this picture shows EWS-liveried 37707 in the Metal Box terminal at Westhoughton in 2003:
https://www.flickr.com/photos/stuarts-phots/5585410349/
Apparently the factory closed in 2003, so that photo would have been from the last year of operation. An RMWeb thread suggests it produced the cans for the local Heinz factory in the Wigan area.
The connection into Westhoughton Metal Box parallels the main line for a fair distance, and from a passing train would give a similar visual impression to a loop (possibly the original layout included a loop here):
https://www.flickr.com/photos/35891004@N05/50681931936/
Booked traction was probably a 37 but it's easy to imagine a 56 being substituted on the day for one reason or another.
Other 56-hauled freight in the area might have been the Knowsley trips, but the terminal didn't open until 2001 and Bolton would have been an unusual routing (normally through Wigan Wallgate, over the link onto the WCML to Golborne & Chat Moss, or direct to Warrington Arpley). 56117 is seen taking the Chat Moss route in 2002:
https://www.flickr.com/photos/8arail/50892092772/
***
Some more detail on the Westhoughton trips:
In the 1987 freight working timetable, there's a 6P82 08:15 Warrington Walton Old Jn to Horwich Speedlink trip. It runs north to Wigan on the main line and takes the connection into Wigan Wallgate before running round in the carriage sidings beyond Wallgate station. It then calls at Westhoughton Metal Box, passes through Bolton to run round at Bolton Burnden Junction, passing Bolton again before reaching Horwich works at 11:11. It then forms 6F82 12:05 back to Warrington Arpley, calling at Chorley Royal Ordnance Factory, running round on the Down Goods at Preston and then direct back to Arpley. In addition to the run rounds at Wigan, Bolton and Preston, all of the sidings served require awkward propelling movements.
The 1984 equivalent of the same trip working is seen at Bolton behind 25032:
https://www.flickr.com/photos/25762703@N03/40661033182/
A nice shot of 40160 at Lostock Junction in 1984 with the same working:
https://www.flickr.com/photos/lickeybanker/51283504555/
Quoting from Paul Shannon's Wagonload book mentioned earlier:
Trainload Metals transferred most of its wagonload steel traffic from Speedlink to its own discrete network in 1989 in an effort to contain costs and increase accountability in the rail freight business
The "
Freight Only Yearbook Vol 1" describes how the Westhoughton trip became a dedicated Metals service from Trafford Park from October 1989 (with Horwich no longer being served by Speedlink, and Chorley ROF served from Blackburn). At this time the Trafford Park railway system was a new origin point for scrap metal traffic to ASW Cardiff, so there was a trunk Cardiff - Trafford Park service with the same loco used for the trip onward to Westhoughton. The
1991 Freightfax (pocket freight timetable) gives the workings:
6M46 Cardiff - Trafford Park (Man Picc pass 04:46)
6F65 Trafford Park - Warrington (Man Picc pass 06:38, Man Vic pass 07:40, Warrington pass 10:51)
6H65 Westhoughton - Trafford Park (Man Vic pass 13:17, Man Picc pass 14:12)
6V46 Trafford Park - Cardiff Tidal (Man Picc pass 20:28)
The daily metals train from Trafford Park to Warrington runs via Ashburys (reverse), Manchester Victoria, Bolton and Wigan (reverse), and its purpose is to serve the Metal Box factory at Westhoughton
As written the workings don't quite make sense, I suspect 6F65 called at Westhoughton (takes 3 hours from Manchester Victoria to Warrington) and 6H65 started from Warrington, but you get the general idea...
From Paul Shannon's book on
Bulk Freight since 1968:
BR carried out a comprehensive review of its Trainload Freight business in 1992/93... the less-than-trainload network established in 1989 was a heavy loss-maker. The decision was therefore taken to close down that network... a few low-volume traffics were lost, such as tinplate from Ebbw Vale and Trostre to Wisbech and Westhoughton.
The freight WTT for May 1993 doesn't have a Westhoughton trip; it had probably ceased earlier the same year. As already mentioned, the Westhoughton traffic resumed during the golden years of EWS Enterprise in the late 90s, so could be the explanation for your mysterious 56-hauled freight.