forms - pros and cons of multi search box vs one search box

I have been asked to come up with a search mechanism for a database. The database stores details about electors.

Is a multiple search field interface better than a single search field interface? The single search can search across all the fields the multi box can.

Drawbacks of single: it can't differentiate between strings that could be a name or part of an address eg 'Woods' vs 'Woods avenue' but the user is not likely going to be searching for something so vague; they are likely to have a unique ID or combination of details eg 'Woods SW6 2LT'

here are the alternatives (state of the system: the user has run some search and the then cleared all the search fields for some reason)

What are the pros and cons of each approach? Are multiple boxes better than one?