Cross Country seem to have caught the GWR^▸ (Great Western Railway) problem. Over the last couple of days there have been significant short formations.

SHORT FORMATION: We are sorry but the 09:00 Glasgow Central to Penzance service is formed of 4 coaches instead of 8 today. Coaches G, I, J and L are not available. If you have a reservation and end up standing as a result....
Also
0925 Penzance to Dundee
https://twitter.com/crosscountryuk/status/1144500668872265730?s=21

The Rosedale Railway ran from the station at Battersby to the iron ore mines in Rosedale from 1861 to 1929. Much of the track can be walked.

https://en.wikipedia.org/wiki/Rosedale_Railway

What had people more concerned was the passenger behind her with their feet on the seat!

This link explains the history of the line, especially the recent history.
https://en.wikipedia.org/wiki/Weardale_Railway

Bus timetables
https://www.weardale-travel.co.uk/wpc2.html

This rail line is fascinating, its main customers were the limestone quarries which operated on the hillsides from Frosterley onwards. The line was operated by BR^▸ (British Rail(ways)) into the 90s to transport cement from Eastgate, which ceased in 1993.
Before then BR ran a Summer Sundays service to Stanhope, extending a Saltburn to B. Auckland train, rather like the GWR^▸ (Great Western Railway) operation to Okehampton.
Hertfordshire Railtours ran an HST^▸ (High Speed Train) up to Eastgate on at least one occasion.

In those days you could then catch a bus to Alston for lunch and return via Killhope lead mine or walk the numerous mineral line connections.
If they upload, this being the second attempt, two photos showing the extent of the mineral railways in the area and a rout description.

0 Middlesborough

In reality it seems that it is only Frome that is affected. Looking at the message I took it to include the others.
The first two up services ran on time, just did not call at Frome.
So might it be better simply to state that trains will not call at Frome?

Other possibilities

https://www.railmagazine.com/news/network/redundant-hsts-proposed-for-freight/passenger-use?utm_source=dlvr.it&utm_medium=twitter

So that must be the Seal Sands branch. Travelled over that on the Tees Tyne Trekker in March 1993.

Is it one of the many cycleways/footpath that County Durham Set up after the lines closed.
However, most of the over bridges seem to be of stone, rather than brick. So, apart from saying the bridge goes West to East, there is not much else I can add

Somewhere between Hartlepool and Eaglescliffe?

It was on a non-electrified line which narrows down the choice. Used Street View to trace the line from Wylam eastwards.
The Tanfield Railway is fascinating, I visited after a trip to Beamish many years ago now.
The whole of the Durham waggonway history and what you can see and walk today is another chapter. The walk up to Bolt’s Law or over the Stockton and Darlington from Shildon to Etherley incline are recommended.
Now, here is one for you, if it has attached correctly!

 Dunston station
Did you visit the staithes?

There was an earlier special 1Z76, the 10.15 to non-stop to Oxford. This took almost an hour, running late until Twyford. It formed the 1Z77 back to Paddington