The majority of the broadcasters in Europe still have teletext services, I know for certain RTE (Ireland), TVE (Spain), ARD/ZDF (Germany), NPO (Netherlands), SVT (Sweden) and Rai (Italy) still have full teletext services. Some of them even have Level 2 services which utilise more colours and better graphics (ARD and NPO). I've got a feeling France Télévisions may have closed theirs at switchover like us, but I'm not sure. They even have them on their HD channels through support on the receivers to access the text services directly from the DVB transport stream, bypassing the lack of VBI support on HD.
The Europeans never adopted digital text like we did, which basically secured the life of the old 'analogue' services on digital. I think we were the only ones to introduce digital text so early (arguably too early). It's only now with the introduction of HbbTV that the Europeans are looking into interactive digital services.
On the note of the test pages, or the engineering pages to more accurately describe them, they can be found all over the text services. They were all there as a way of the engineering teams to quickly check that the central server and the regional network were all in correct working order, and which parts had gone wrong if not.
Most (if not all) the regional ITV text services had a page on 6AA which show the status of the local teletext inserter and when it was last updated over the network, for example this is Granada's: http://al.robotfuzz.com/~al/teletext/itv/2000-05-05-0048.3/6AA.html
Teletext had theirs on 379 for most the 90's, for example this one from 1995 showing the network with a problem somewhere: http://al.robotfuzz.com/~al/teletext/itv/1995-11-04-0003.5/379.html.
Looking at the recoveries it seems the page disappeared around April 1998, replaced with normal content.
DBI, the company who used the VBI lines for the 700 magazine on ITV to provide a data transmission service to betting shops and the like, also had one on 799: http://al.robotfuzz.com/~al/teletext/itv/1998-04-14-0036.10/799.html
They were hexadecimal page numbers, my memory of the queue pages Insp Sands mentions were that they
were on 6AA or higher which I accessed by stepping the + button beyond 699 ? I'm sure deep inside the 1974 BBC/IBA/BREMA spec it said that the receiver should suppress such pages, but manufacturers often love to ignore specs.
I'm not completely sure of the original spec, but I know the current ETSI spec states that page xFF (with x being the magazine number, eg 6FF) should be assumed to be a timing placeholder and ignored, as well as subpage 3F7F. By the ETSI spec 6AA is a valid page.