All:

Thanks for the info and advice. Here´s a quick update:

Left the USA on my UK passport and entered Spain on the same. No worries at all.

Tomorrow I leave for the USA and earlier today I visited the US Consulate in Valencia with all of my documentation [expired US passport, Naturalization Certificate, recent tax return, US driver´s license] but, no joy. The unfriendly woman told me to go to Madrid tomorrow [the day I am leaving] and visit the US Embassy. I dunno´about you, but when a citizen arrives at a US consulate with all manner of proof of US citizenship, it seems they could do something to help. Put a call into Madrid and fax the documents? Provide some emergency documentation? Seems like bureacracy at its finest.

Anyway, I´m going to leave Spain on my UK passport and I also have my approved ESTA which should mean I can get out without any problems. On entering the US, I´m tempted to use the US Immigration line as it´s faster and, as stated above, I have more proof of identiry documentation that you can shake a stick at. I may get a verbal beating, but I cannot imagine they would put me back on the next plane to the EU when, again, I have more proof of US citizenship than most natural-born Americans. They wouldn´t, would they?

Wish me luck and if you see me on CNN being waterboarded in Gitmo, you´ll know that I failed to make it through.......

Smethwickman