The British monarch made the comments at last night's glittering event inside Buckingham Palace, just hours after the Spanish king addressed both Houses of Parliament.
The first time they went up for auction, there were no buyers.
This was the first state visit for a Spanish royal since King Felipe VI's father visited the U.K. 31 years ago.
He added 'through necessary dialogue and effort, our two governments will be able to work towards arrangements acceptable to all'.
The Queen's engagement news in 2003 came as a shock to the country as it was not common knowledge that Felipe was romantically involved with anyone.
The Dean of Westminster John Hall was on hand to welcome his guests of honour, and led the group inside for a tour.
Gibraltar's chief minister Fabian Picardo said that while the population wanted friendly relations with Spain, their position on sovereignty remains clear. Spain, however, continues to press its claims to the territory.
Mrs May hailed the'deep and solid ties between Britain and Spain today
"These citizens have a legitimate expectation of stable living conditions for their families", he said.
He adds that Britain is the "top destination for Spanish investment in Europe".
Before meeting her future husband, the 44 year-old was a very successful TV anchorwoman, working with CNN, Bloomberg as well as Television Espanola.
Not only does Letizia drop off and collect her children from school, but she also takes the underground, attends concerts with friends and has been known to (shock, horror!) wear jeans. In sectors such as banking, Spain is the second- biggest investor in Britain behind the United States. "And that deal must also work for Gibraltar". The 116,000-odd Spaniards in Britain are mainly workers. The long-line collarless lemon blazer featured a minimal style and textured fabric, and complimented the royal's slimline physique.
The Spanish queen looked as fabulous as ever in her ensemble, teaming a crisp white wrap blouse featuring an asymmetric neckline, with a midi-length pleat front skirt from the renowned British brand.
The king said Echeverria behaved in "an exemplary and heroic manner".
Prince Harry has accompanied the king and queen of Spain in a wreath-laying ceremony at Westminster Abbey.