This has been around awhile, but one of my British buddies pointed it out to me today.
It's a fan trip behind "Oliver Cromwell", during which it parallels and runs neck and neck with a Black 5, deadheading back home. If you haven't seen it, this will plant a seed of what we might someday see here, perhaps, maybe, if we all wish hard enough.

http://www.youtube.com/watch?v=niR9TwUglXI

The engine crews must have been in radio contact, as "Cromwell" overtakes the other train several times and then falls back.

Been done here before. Google "1218 611 nrhs convention pacing 1987" and you'll find all kinds of stuff on a trip just like that.

NS, are you listening?

The difference is that the 611/1218 and 1225/765 events were intentionally staged at slow to modest speeds. The 70013/44932 occurrence was completely spontaneous.

No radio contact was necessary. Observe the driver of the Black Five watch the train overtake him, then he gets back in and cracks open the regulator. And they're both galloping at track speed.

That would be like having the 844 and the 4449 on two different trip which just happened to share the main line together at some point. What a bonus that would be!

They did that going to Los Angeles in 1989, racing into the station, no less!
They also double headed through to the Puget Sound more recently, in 2007:

Here's the race from a different perspective. Gives another idea of what they can do in Britain.

http://www.youtube.com/watch?v=t__zpwemTdA

Interestingly, "Cromwell" was a park locomotive at one time.

As the Brits would say, "brilliant, absolutely brilliant!" Must be something like what one would have seen 60 years ago East of Chicago, with the nightly "race" between the Broadway, and the 20th Century Ltd. Just a hint of that, mind you. On the second video, from the ground, I really like that no one went nuts verbally when they realized what was coming at them, like would certainly happen in a photo line here, just a rather calm comment at the very end of the clip.

Is this 2 different Main Lines that later separate?
TAN: I rode the last of a similar, but non steam, race. Near the end of April, 1958, I rode the Rail Diesel Cars on the last Daylight Speedliner on the Baltimore & Ohio RR from Washington's Union Station to 24th St. Station in Philadelphia. It was scheduled to leave at 5:55 p.m., but the engineer delayed so he could race the 6:00 p.m. Pennsylvania RR GG-1 electric locomotive and train bound for New York. My train quickly accelerated to about 80 m.p.h. before the competition could reach that speed. However, the other train was scheduled to arrive in Philadelphia 5 minutes before mine.

It's been done with geared engines, too:

http://www.youtube.com/watch?v=4cMT_T1CDbM

Of course, what we really could use--and would dare say, the railroad industry as a whole could use--would be regular or semi-regular main line steam operations. But how do we get to that?

The othr almost important question is would there be much demand for more main line running? How many more paying passengers?

A comment from a friend of mine with reference to the thought these two Brits are "racing":

"with reference to the two British steam locos running side by side, they are on different divisions. Would you please inject (on RYPN) the fact that they are not racing! They are governed by a speed limit on this division. They are merely running parallel. RYPN posts say they are racing, and they are not. I am in touch with two British friends via e-mail every day. The trains are not racing.
It would not be tolerated there no more than it would be here. Every region on every railroad there and here have posted speed limits.

Just to tidy up the thread.

This Wikipedia link was found from a Wimp video (wimp.com/secrethero/):

http://en.wikipedia.org/wiki/Winton_Train

It tells of the departure from Prague's Main railway station on Sept. 1, 2009 of a train for England running exactly 70 years late due to the war. Numerous steam locomotives from 4 countries that could have pulled the train if it had been on time were used to haul it across 3 countries on the Continent. The connecting train in England was pulled by that country's newest steam engine.
(I wonder if any of the original ticket holders survived to finally take the trip?)

And we worry that Mr. Rowland's Yellow Ribbon Express is daring!

I have witnessed the great Cass side-by-side show, and even got to ride the cab of one of the Berks for their side-by-side, but this video represents something entirely different and all around spectacular. Love it.

Rob