Tell me the bridge that is located in the administrative territorial entity of London borough of Southwark and starts with the letter b?
SELECT DISTINCT ?sbj ?sbj_label WHERE { ?sbj wdt:P31 wd:Q12280 . ?sbj wdt:P131 wd:Q730706 . ?sbj rdfs:label ?sbj_label . FILTER(STRSTARTS(lcase(?sbj_label), 'b')) . FILTER (lang(?sbj_label) = 'en') } LIMIT 25 
bridge: Q12280 london borough of southwark: Q730706