Their gaff their rules.

Yes its muslims... again.
I'm of the opinion that your employer decides just what goes on in his premises. Dress code, health and safety basically what you can and can't do, so long as its within the law. But as we all know, islam and muslims have their own interpretations of just what they can and can't do and aren't afraid to get litigious about it.
Mail.

Two Muslim Tesco workers have won a discrimination case against the supermarket after bosses kept their prayer room locked.
Abdirisak Aden and Mahamed Hasan, both aged 27, were among a number of devout Muslim employees who had lobbied for a prayer room since 2006.
In 2008 managers agreed to set aside a security office at the distribution depot in Crick, Northamptonshire, as a prayer room for Muslims.
But in 2012 bosses set new restrictions on the use of the room which included keeping it locked when it was not in use.
Muslim workers were forced to tell managers when they were going to pray and had to ask for the key and fill in their names in a book every time they entered the room.
They also claimed they were forbidden to worship in groups and were only allowed to pray one at a time.

Is it just me, if you're praying, then you aren't working, if you aren't working, then you don't get paid? It's not like it's a call of nature now is it?
Express.

TWO teenage Muslim pupils have been banned from lessons after refusing to shave off their beards for school.
The school says the 14 year olds are breaching its dress code and has placed the boys in isolation, sparking a row with their parents.
The boys’ families claim they are suffering discrimination because beards are a symbol of faith and their religion forbids them to shave.
However, the Mount Carmel Roman Catholic High School in Accrington, Lancashire, has conducted it own research which concludes the boys are not required by the Koran to wear beards, and it is merely their choice.

Pretty much a case of the muslims not knowing the quran which doesn't mention beards or shaving and more a cultural desire to emulate the murderous, misogynistic, bigamistic, paedophilic, murderous warlord founder of the islamic cult.
Now as far as I'm concerned (though not the judge) Tesco's have set aside a room for muslims to pray, most other groups would either do it outside of work or as they are working. They won't allow groups, after all who wants he workforce knocking off in bunches to chat to their sky fairy? They're supposed to be working after all and if they can't cope without knocking their heads on a mat for part of the day alone then perhaps they ought to go somewhere else.
As for the boys, well the school has its dress code and religion ought not to trump the code, I doubt anyone else would try this tack except of course muslims. It's the same with the veil and the desire to knock off and pray. If you want to do that in your own house or on the street (so long as you don't block the traffic) then fine, but you don't get to say so in my place or in anyone else's place who says you can't.
Same with the schoolgirls mother who was going on about her daughter not being allowed to wear a 'Help for heroes' bracelet in school. It's a good cause, but it's against the rules.
Live with it, because using the law to enforce your rules is storing up a lot of trouble for yourself in the future.