Great Western Coffee Shop

(http://farm5.static.flickr.com/4142/4808194386_23c2404d14.jpg)

Any idea which part of the country?  or which Operator?

First set of clues:

1, I caught a fairly new DMU from here. 

2, The station also appears to be a token exchange point (a man came out of the signal box to hand the driver a leather pouch on a metal hoop)

3, I believe that the signal is of a somewhat unusual type which I think you can just make out of you look closely

4, The original station building appears to have been converted into a bar/bistro

5, There are no ticketing facilities on the station.

That looks a pretty manky signal. And it hasn't got a number on it.

Are we in Northern Ireland? On the line to Londonderry?

Thanks for that pointer W_P.

It's Castlerock on the Belfast-Derry line.

The 'fairly new DMU' would've been a NIR Class 3000 I suspect.

Correct.  Well done.

The signal is a summersault type with a pivot in the middle.  I hadn't noted it lacked a number, but it seemed to be just protecting the crossing along with one on the other side and corresponding distance signals).

This is what it looks like in the off position.

(http://farm5.static.flickr.com/4138/4811362979_de700efc01.jpg)
I didn't notice the class number but "CAF" was the manufacturer on the makers plate inside so you are probably right.

No ticket machine at the station means I boarded intending to buy a ticket from the guard.  But was I to ask him for a return to Derry or Londonderry (I prefer to stay neutral in other people's arguments)?  I decided I would avoid the issue by asking for a ticket to "waterside station" or "the end of the line", but in the end he didn't come round I was able to buy a ticket on arrival "from Castlerock" 
(http://farm5.static.flickr.com/4073/4811362563_22433a5aae.jpg)
  Waterside station

There was me with complete tunnel vision trying to work out where in East Anglia NR's last remaining ex-GNR somersault signal was still soldiering on!  :-[ I know there did used to be at least one left in service, is that still the case?

http://www.signalbox.org/last/signals.htm (http://www.signalbox.org/last/signals.htm) reports the remaining somersault signal as being at Boston Docks Swing Bridge.

http://www.signalbox.org/overseas/ireland/castlerock.htm (http://www.signalbox.org/overseas/ireland/castlerock.htm)

has some more info about Catslerock's signals, Including aphoto which looks very similar to mine but is 10 years older