Ask an Immigration Solicitor. Get an Answer ASAP.
Has your partner informed the Police and UK embassy in Germany? Do you have a copy of his visa?
What type of visa should he have?
He needs to apply to transfer his visa. Follow the link provided https://www.visa4uk.fco.gov.uk/home/welcome He would need to send a copy of his visa and the emergency passport he has.
here is further information regarding this issue https://www.gov.uk/government/publications/transferring-a-visa-to-a-new-passport-ecb17/transferring-a-visa-ecb17#ecb172-replacing-a-visa-or-leave-where-this-has-been-lost-or-stolen-excluding-30-day-short-validity-travel-vignettes
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