changing trains in Doncaster with 7 minute connection time

1) If trains are on time, no problem, as otherwise they would not sell it.
2) You will be permitted to take the next train. After all, LNER must get you to London.
3) Permission to board a train is not contingent on there being seats. This is not air travel. Of course if more people board a train then there are seats some people will stand.

But in your place I would just take one of the direct trains...

Just take a direct train without the need to change. But yes 7 minutes is enough time.

For those wondering why I am not taking the direct train, there is a simple answer:

the direct train is more expensive.

hence the attempt to see if this will work.

That is unusual for Hull trains to be more expensive than LNER. The opposite is normally the case. The connection should be cross or same platform. It's a bit tighter if the incoming train uses Platform 0 at Doncaster.
You could cover your bases by booking a seat (only) on the following train using the GWR website.
I've done that for Sunday- Booked seats only for trains I don't currently have tickets for. I will buy tickets on Saturday.
7 minutes is the MCT (Minimum Connecting Time) at Doncaster.

It is not that the Hull train is more expensive it is the direct train is either before 9:30 am and is therefore more expensive or 2 hrs later and gets into London too late. This one is just right.

But honestly I am getting cold feet wrt transfer time so will probably end up paying the higher price.

Thank you WengenK and Camborne2018 for replying.

As you are saying 7 minutes is enough connection time is there any reason you are advising to take the direct train?

For example - Is it very cumbersome to change platforms in Doncaster? Are the trains often late? Are there long waits for the next train? The time table seem sot indicate that Doncaster - London service is fairly frequent?

Getting off a London bound Hull trains service to join an LNER train is a very strange move. The two companies are not best buddies to be polite about it.
That is not a recommended move.

It would be very different if you were changing from Northern to LNER.

Have a look at the Scotrail website and see if Hull Trains have a split ticket on Doncaster where you just stay on the same train but have two tickets. Doncaster to London is a competitive market so that may be the case.

AH checked again it is NOT a Hull Train it is Northern

09:38
Brough(BUH)
Platform 2
12:21
London Kings Cross(KGX)
Platform 0
2h 43m, and,1 change
Route Details - 1 change

Transport method is Train Service
09:38
On time
Brough
Platform 2

1 stop
10:18
On time
Doncaster
Platform 3B

Transport method is Train Service
10:25
On time
Doncaster
Platform 1

5 stops
12:21
On time
London Kings Cross
Platform 0
1h 56m • London North Eastern Railway

It is cross platform at Doncaster station. Takes 1 minute.
https://images.nationalrail.co.uk/e8xgegruud3g/1gex4Nou3yi7Fgg1h74orL/08e55d5f37694853a6479c69873c1aa7/Doncaster_station_map.jpg

That is a cross platform change- no steps or underpass. The first train should be 3 minutes early.
It goes on to Sheffield so has to use Platform 1 or 3.

If it is late the next LNER trains are 20 and 30 minutes behind.

Quite happy with that.

Thanks for the reassurance. May I ask what do you mean by the first train should be 3 minutes early? Is it usually early? (if so that is lovely!) Or are you saying it needs to be early in order to make the connection (hoping not)

Are there sites where you can look up how late / early these trains have run historically?

The first train has 3 minutes of "recovery" or "slack" time built into it's timetable.
So if it was running a bit late out of Hull that is spare time built into the schedule.
Today the real times trains website show it made up more time than that and arrived at Doncaster 5 minutes early.

I live in Hull and do this journey a few times a year. I much prefer to get the Hull Train direct to London but as stated. I’ve done this journey plenty of times and never had a problem with the connection.