Prime Minister David Cameron's spokesman has confirmed Britain is "seriously considering" taking legal action against Spain over extra checks at the border with Gibraltar.
The spokesman said the tighter checks by Spanish officials, which are causing long delays, are "politically motivated and totally disproportionate".
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The district's director of homeland security has said officials are planning for 800,000 to 900,000 people to attend the ceremony.
The Supreme Court is set to decide on whether disabled travellers are legally entitled to have priority use of wheelchair spaces on buses.
There will be some brightness, with the best of the sunshine towards the south and southeast where it will again be chilly.