I don't understand why One Foot in the Algarve would need restoring.
Admittedly it's 30 years old now, but this was made at a time when vintage programmes were treasured, and lost programmes were much sought after - so surely this programme should have been preserved and kept in pristine...
If they brought that show back, with the same actors, 34 years after it ended, I suppose the show would be somewhere around 1973 - when the original programme began.
Technically they could make new episodes that would complement Series One of LOTSW.
Of course, it wouldn't be the same.