Many national 20th Century newspapers were reproduced in the 60's and 70's as free inserts for various weekly magazines; usually these were to illustrate major historical events outlined in the publication.

The editorial content of the magazines consisted of  various disasters or triumphs, especially the World Wars. The inserts reproduced were not only British newspapers but also foreign papers, all had major headlines.

Also many national and local special editions have been and are still being reproduced for anniversaries of historical events.

Usually it is quite easy to spot a reproduction from photographs, especially if the genuine newspaper originally had a coloured logo and this is lacking, i.e in WWII the Daily Express had a red crusader and this continued post war, the Daily Mirror/ Sunday Pictorial usually had red title letters, post war  the letters are white in a red box. The Daily Mail had a red edition cachet or logo to the right of its mast head. Other titles often had coloured cachets e.g Stop Press associated with them eg. Daily Herald and Daily Sketch, but unfortunately not always. 

Local newspapers seldom used colour, so a coloured logo/cachet is a bonus, there are also national daily papers that rarely or never had a coloured logo.

So a coloured logo/cachet is a good indicator.

But to make life really difficult recent reproductions sometimes include coloured titles (even occasionally when the original title was in black and white!), but these are a different shade and brighter when compared to the original. They are generally produced in packs, with a common theme e.g. Royalty, Disasters, 60's etc. They are available for National Curriculum studies and also general interest. These packs are often to be seen on the e-bay site and are really useful for students.

For those papers that usually do not have any coloured markings associated with them, it is really difficult to decide from a photograph if they are genuine, especially early 20th century papers, also the Daily Telegraph, the Times, Observer and News Chronical, but there are still markers to look for.

Look at the centre of the paper, as many early reproductions were essentially photocopies so you can see an image of the fold mark of the original paper and this will disrupt the text on the front page and subsequent pages.Also the edge mark of the original paper is obvious as a black line at the top or side of the page, but generally this is something you can only judge with the papers actually in your hand. Likewise the print and paper quality cannot be judged from photographs, modern reprints are printed on much finer paper than the originals, which often appear dull in comparison.

If seller has lots of major headlines check them carefully or if the photograph of the masthead is incomplete be suspicious.

Remember that papers produced in the 60's and 70's will, by now, have an aged look to them.

Some of the reproductions are not even in a newspaper format e.g. being seperate sheets or the pages are out of order! 

Some anniversary editions actually have "reproduced by permission" printed on them! 

There is a place for reproduction newspapers, especially for teaching purposes. As a collector I avoid them, but it is so easy to get caught out from a photograph.  

Also remember too that these were free with the magazine or special issue, so do not pay an exhorbitant amount for them!

I have always found dealers to be honest and quite shocked when they find that the item is not quite what it seems, but as a collector for 40 years I know what to look for. 

I believe that there is something quite special about an original newspaper, as you are holding a little piece of history and reading about a unique moment in time!

I also feel that these reprints should be described as such and not passed off as genuine to the unwary.