Further to my item about passports being stamped, I have now read about inconsistencies at Alicante Airport.
It seems that some, who have shown both their passport and TIE card, have still had their passports stamped. Others have just been waved through without even examining their documents.
CSB, the bureau who handle our legal affairs here, tell me that we should have proactively shown both our passports and TIE cards at the Spanish border. The fact is we didn't but from what I have read, it may not have made any difference anyway.
Following the end of the transition period, the rules about how long you can stay in Spain as a non-resident are being applied (90 days in 180). If you are not a resident and have stamps in your passport that indicate you have been in the country longer than 90 days, you could be classed as an illegal overstayer which would mean you would be denied entry on a subsequent visit.
NB The 90 day rule applies to all countries in the Schengen region. Those who are not European residents need to keep a record of how long they have stayed in any of the countries covered by the rule and make sure the number does not exceed 90 out of 180.
PS I've read that the stamps are meaningless because the dates are recorded electronically on your passport when it is swiped. However, when we left and returned to Spain, our passports were scanned but not swiped. It was only in Manchester that our passports were swiped at the border.