EU vote will clash with Euro 2016 and Glastonbury
The date of the EU referendum will see a clash with some other major events in the sporting and music calendars.
The Prime Minister said June 23 will be a day on which the country makes one of the biggest decisions "in our lifetimes" - but thousands of Brits may be elsewhere.
Masses of England, Wales and Northern Ireland football fans could still be in France if their teams make it through the group stages of the Euro 2016 football tournament.
England and Wales, who are both in group B, are due to finish their group matches by June 20, and could still be there by the end of the week if they make it through to the last 16.
Northern Ireland are set to have their last match in group C on June 21, and will remain in France should they make it through, with the first of the knockout stage matches scheduled for June 25.
Meanwhile, Glastonbury music festival will be into its second day by the date of the referendum, and the prospect of revellers casting their votes on the sprawling campsite has already been ruled out.
A petition to host a polling station at the festival was drawn up on the Parliament.UK website earlier this month, but rejected as polling stations are not the responsibility of the Government or Parliament.
Asked about having a polling booth at the festival a spokeswoman for the Electoral Commission said: "Legally it's not possible. The rules are the same as they would be for a general election. Polling booths can't just be set up."
Labour councillor John Fulham, who wants the UK to remain in the EU, tweeted shortly after Mr Cameron's announcement: "Looks like I'm definitely not going to Glastonbury."
Other music fans drew their own conclusions at the Government's plan to hold the referendum on the same date as crowds of young people descend on the festival.
One student wrote: "The cynic in me thinks it's no coincidence that David Cameron has put the EU referendum during Glastonbury weekend."
Another user said: " The EU referendum is during Glastonbury. Is that 150,000 votes lost for remain?"
No-one will have to lose out on using their vote, the Electoral Commission spokeswoman said, urging people to get organised as soon as possible.
Absent votes, either by post or by proxy whereby you can nominate someone to vote on your behalf, are available.
The spokeswoman added: "There will be a public awareness campaign to let people know exactly how to get registered. It takes under five minutes to register.
"No-one should miss out. Just get organised."
A tweet from the official Glastonbury account directed people to the Government's website on how to vote.
It said: " It won't be possible to have an #EUreferendum polling station at Glastonbury 2016. You can register for postal votes."