This is unbelievable and sheer vindictive racism on the part of the OP – it has been moved from the 'No Irish Need Apply' thread in order to keep this blatent campaign against Traveller alive.
For the thirty years we worked with Travellers in London and the Home Counties, Birmingham and Bristol these signs were not only commonplace, but it was extremely rare to find a pub that would serve Travellers.
We went round London in the late 80s and early nineties with Travellers photographing them in order to assist the campaign for having them removed.
Our CD of Traveller songs 'From Puck To Appleby' has one of them in the notes – see Musical Traditions website which carries the full notes and photographs if you have any doubt
Despite the fact that it is illegal, many pubs still carry the signs, and others, while technically obeying the law and not displaying them, they refuse to serve Travellers
The last time we experienced it personally was in Bristol in 2005, which was the last time we recorded a Traveller
I would not have believed that anybody would go to such lengths to disprove one of the most well known facts regarding racism towards Travellers in Britain   
The OP's only argument against these facts is that he has never seen one so they don't exist.
The below addresses all carry references to the practice still going on – there are many, many more to choose from.
Take your pick
Jim Carroll

http://www.leicestershiretogether.org/gypsy_travellers_the_truth.pdf
Gypsies and Travellers can experience unequal treatment from the police. They cite stories of being arrested without due cause, unfairly barred from public venues, or repeatedly stopped and questioned. The CRE in 2004 pointed out that some forces are working to improve their equality strategies and practices, but in many areas there is a long way to go.
There are still 'No Travellers' signs in some pubs and shops, where Gypsies and Travellers face suspicion and extra scrutiny by security guards. Evidence also points to Gypsies and Travellers being prevented from entering cinemas and facing discrimination at fast food/restaurants and other retailers. In July 2008, Travellers also alleged that they were turned away from the Royal Windsor Horse Show.17 There can also be problems with getting taxis to drop off at sites. Gypsies and Travellers can and do meet outright public hostility and racism. Gypsies and Travellers are often the target of racist incidents, which can include verbal abuse, inappropriate jokes, damage to property, physical assault and even murder.18 Chants at football matches that equate players with long hair to living in caravans remain common to this day, whilst other stereotypically offensive and racist chanting has largely disappeared from UK football stadia. Leicestershire's Hate Incident Monitoring Project is a good source of information on hate incidents, including those of a racial nature.
http://www.gypsy-traveller.org/your-rights/law/harassment-and-discrimination/ Types of Discrimination

http://citynewyorkstatenisland.academia.edu/PeterKabachnik/Papers/870967/To_choose_fix_or_ignore_culture_The_cultural_politics_of_Gypsy_and_Traveler_mobility_in_England
http://www.c-s-p.org/flyers/9781847181275-sample.pdf
http://www.amazon.co.uk/No-Gypsies-Served-Miriam-Wakerly/dp/0955843219
http://www.travellerstimes.org.uk/downloads/TT39_27052009165255.pdf
http://www.gypsy-traveller.org/your-rights/law/harassment-and-discrimination/
http://www.morningadvertiser.co.uk/Forums/News-Article-Comments/Pub-manager-sacked-for-no-travelers-sign
http://www.getsurrey.co.uk/news/s/2118593_gypsies_to_feed_in_to_education_and_health_surveys
http://www.getsurrey.co.uk/news/s/2118593_gypsies_to_feed_in_to_education_and_health_surveys
http://en.wikipedia.org/wiki/Antiziganism
www.equalityhumanrights.com/uploaded_files/Wales/njas_gypsy_
http://www.chavspace.com/news
http://www.journeyfolki.org.uk/Community/HelpResources/CommissionForRacialEqualityCRE/tabid/832/language/en-US/Default.aspx