Ah, thanks DCI. Not very ill-fated at all then, rather the opposite, a lot more people visit towns & villages during fiesta times than normal.
I think you'll find it was the McCanns rather than myself who were disappointed hat it was a bank holiday 
Actually from Kate's own words there was no sign of the disappointment you have claimed.
It had been their intention to go the previous day but that was thwarted by them receiving an early morning call from the police to remain in PDL. Eventually at 5pm they Police turned up to collect all their clothes and many other posessions for the dog checks.
Nonetheless the following day they carried out their intended visit to Huelva to help in the search for their daughter.
"We finally made it to Huelva the following morning, so all was not lost on that front – even if we did discover when we arrived that it was a public holiday. It didn’t matter: the local people were so kind and obliging and we came back feeling that it had been a very productive trip."Page 207 First Edition Hardback