Until 1991, there was no standard design for BBC trailers. Instead they would make use of any layout and fonts that the producer of the trailer felt like using.
They would, however, sometimes form part of a seasonal promotion, where trailers would be bookended with a short filmed or animated sequence. These were used particularly for the autumn and new year seasons of programming, but also at Christmas, Easter and during the summer months as well.
As part of the BBC's presentation revamp of February 1991, a standardised design layout was brought in, with the programme title and time appearing at the end using the Futura font, along with the channel logo in the top left corner. From March 1993 the latter would remain on screen throughout the trailer.
Seasonal promotions continued, however - the example shown above is a summer-themed sequence from 1992, used as part of a trailer for the comedy series Side by Side.
In other cases, the programme title and transmission time would appear over scenes of the programme itself, and this would always be the case following the demise of seasonal promotions outside of Christmas in 1993.
From October 1997, the trailer design was almost identical to the design of programme slides, with the addition of day and time, and likewise would now be identical across all BBC channels.
Trailers on the UKTV network of channels also followed this design, until a revamp in May 2001 when the Gill Sans font was replaced by Univers.
BBC Choice, meanwhile, partially broke away from the standard layout in July 2001, when it introduced its new idents featuring three orange boxes. The logo remained at the bottom of the screen, but the programme details were now displayed at the top right of the screen.
In the early 2000s, the BBC's channels each moved away from the standard format with their own distinct trailer endboards. BBC1 used transparent white strips from the introduction of the 'Rhythm and Movement' idents in March 2002, changing to garish red shutters in May 2004.
Red swirls accompanied the launch of the circle idents in October 2006. The 'Oneness' era from January 2017 saw the logo move to the bottom of the screen, a darker shade of red and the text appear at a larger size, but in the same bespoke font as before.
BBC1 trailers would frequently eschew the standard endboard format, however, particularly those for major new series, and instead finish on scenes of the programme or other appropriate imagery, with a screen layout similar to that used from 1997-2002. Programme logos would also sometimes be used at the end of trailers.
Trailers from the personality '2's era between November 2001 and February 2007.
With the launch of BBC2's 'Window on the World' idents in 2007, the trailer endboards would now feature scenes of the programme viewed through the '2'.
The channel's revamp of its trailers in June 2009 saw the '2' at more of a jaunty angle. Despite drawing much criticism for some unsuitably bright colour schemes, this design would remain all the way until 2018, albeit with some amendments to the way the text was displayed in 2017.
From September 2018, BBC2 simply used its new 'Curve' idents to lead in and out of trailers, with the Reith font animating between serif and sans serif versions, though this curious practice was later dropped.
BBC3 trailers from the blobs era, dating from 2003, 2005 and 2006.
A variety of different styles were used following BBC3's revamp in February 2008. The next major update came in October 2013 with a much simpler endboard style.
BBC3's presentation was updated once again for its move online, and was accompanied by the introduction of its 'tricon' logo. The first image here dates from January 2016, shortly before the demise of the linear channel; the second is a revamped style from 2018. By 2020, the 'tricon' had been relegated to the status of secondary logo, in favour of a more conventional logo spelling out the channel name.
BBC4 has also regularly revamped its trailer endboards. These images date from early on in the channel's existence, in 2002.
This style of endboard accompanied the introduction of the long-running 'four perspectives' idents in September 2005.
BBC Four switched to using full-screen endboards in autumn 2007, and came in a variety of different colours. The design was revamped in 2013 and again in 2018, the latter time introducing the BBC's own font, Reith.
Trailers from BBC 2W, the Welsh digital-only opt-out of BBC2. These images date from 2001, shortly after the launch of the service, and a later style from 2004.
BBC News 24 trailers from 2002 and 2003, featuring a similar screen layout to BBC2's trailers from the same period, and different styles of boxed logo. Also shown here is a much more recent trailer from the BBC News channel, from 2021.
BBC Parliament's trailers retained the 1997 format for years after the other channels went boxed - until 2006, when a red box was introduced to its trailers. However shoving such a long name into a small box clearly didn't work very well, and by 2010 it had reverted to the previous style.
Sports trailers in the late 1990s/early 2000s followed the standard layout of the time, but made use of a 'BBC SPORT' logotype at the bottom of the screen rather than a channel name. Since then, they have tended to use custom designs - these examples date from 2010, 2014 and 2018.
With the rise in on-demand viewing, trailers have increasingly been used to promote the availability of programmes on iPlayer. The examples here date from various times between 2014 and 2021.
By late 2020, the programme title and iPlayer logo were being displayed separately, with the BBC blocks now coloured pink in line with the iPlayer logo. The original 1997 guidelines for this BBC logo stated that it should only ever be coloured black or white - seeing it like this, it's easy to understand why...
From its launch in 2019, the BBC Scotland channel made use of some decidedly garish colours for its trailer endboards. Its Gaelic language counterpart, on the other hand, was much more restrained in style.
20th October 2021 saw a new design for trailers introduced across the main BBC channels. The standard format, shown here, uses a different colour scheme for each channel (the pinky-purple is for iPlayer).
As before, however, many trailers, particularly those for major new series, use a different screen format, which makes use of the programme's logo across the centre of the screen.
Finally, a look at trailers from CBBC and CBeebies.
These styles were introduced in 2001, 2002 (accompanying the launch of the CBBC channel) and 2005.
CBBC's new look in 2007 included a revamped style of trailers. The next major update was in 2016 (these two examples date from 2021).
CBeebies's trailers originally used a similar design to those on CBBC. The format as seen in the second image was introduced around 2009, and was still in use in 2021.