CRB has found the vote counts I was looking for, on the El Pais website. Sadly not as conclusive an increase in voter turnout as I was hoping: 77% is above average but similar to previous years, including 1996 as the above link states.
Surely that must be it, though? As CRB says, can you imagine a PSOE–PP floating voter? David Aaronovitch is just about swarthy enough to satisfy the physiognomy along with the politics (if those could be made far more extreme than what he currently holds), although he’d probably need a salt-and-pepper moustache.