Here are sequences of four - what would come fifth?

1.
'Most bashed' rail bridge hit three times in a week - Ely, Cambridgeshire
Helen Whatley and Wera Hobhouse - transport spokesmen for Cons and Lib Dems
Red Funnel ferries, Isle of Wight - merged posts, ongoing developments
The final batch of trains from York works - two different futures

2.
Sir Brian Robertson
Vanguard
Formidable
Albion

3.
Sir Stanley Raymond
Sir Henry Johnson
Sir Richard Marsh
Sir Peter Parker

4.
PN
RG
DY
SN

5.
Covingham and Nythe
Eldene and Linden
Great Western Hospital and Badbury Park
Middle Witchel or Great Western Hospital

6.
Cannon Street - Blackfriars or Holborn Viaduct via Metropolitan Junc
Charing Cross - Hastings via Orpington and Battle
Cannon Street - Hastings via Orpington and Battle
Charing Cross - Gravesend or Maidstone West via Sidcup

7.
George Borrow
The Tamar Kingfisher
King Edmund
The Coastal Connection

 
3. Sir Robert Reid

 
2 D804 Avenger

 
4. CM

 
6.  I guess that this this might be Southern Region headcodes

 
Try again, 7 Peter West OBE, named class 150 units.

 
Just 1. and 5. to go ... and 6 to finish off.

 
11, 22, 33, 44 so next is 55 (Cannon Street - Gravesend or Maidstone West via Lewisham and Sidcup)
1981

 
1.     Southampton Airport (and TransWilts links to it)

 

Wow, yes, you are correct. Why

2 is indeed 'Avenger' - Warship names

3 is Sir Robert Reid - chairs of British Railways Board

4 - CM is a good answer as would be BY or KE - first and last letters of express stops out of Paddington

5 ??

6  Cannon Street - Gravesend or Maidstone West via Lewisham and Sidcup - head codes.   My understanding is that early southern units carried a set of stencils numbed 0 to 9 to make uo 2 digit head code so that the multiples of 11 were left out until the Hastings units came along ...

7 Peter West, OBE

 
5 something to do with Swindon bus routes?

 

That's what I worked out too. But the sequence of four that best matches the clues has no fifth member!

 

2, 14, 1, 11, x

I have heard of platform zero, but not a bus.

 

Yes I have been working on that if they are routes from the bus station
  ah yes its Wroughton

 
5 is not the Route numbers but the stands they leave from in the bus station  U, V, W and X  so the next is Y from where the No 9 goes to Wroughton.

 

Obviously these are forum threads - or topics, in technical terms. The last one if you look at it contains a post from Graham saying "I have just noticed - we have reached a milestone - this is topic number 25,000!". So that's a basis for a sequence, isn't it? And the topic numbers are 31,000 29,000 27,000 25,000 23,000.

The post also contains this: http://www.passenger.chat/25000. That syntax does provide a way of quickly finding a topic from its number. However, I did not spot that at first, and when I did it didn't work first time (I find it's rather hit and miss). Fortunately 23,000 happened to be on the board I looked on first!

 
I'm thinking we should put together an "Only Connect" team ...

 

That's the sequence I found, but stop Y was not in those maps and lists, no doubt because they were produced by Swindon Bus Company. Route 9 is a Stagecoach one, so it only appears in maps made by the council. So you need a bit of local knowledge ...