LONDON, Dec 9 (Reuters) - An investigation into alleged lockdown parties in Downing Street last year will look at three gatherings and could become a police matter if evidence of law-breaking is uncovered, a junior cabinet office minister said on Thursday. Paymaster General Michael Ellis said the investigation, announced by Prime Minister Boris Johnson on Wednesday, would look at alleged gatherings at Number 10 Downing Street on Nov. 27 and Dec. 18, as well as a gathering at the Department of Education on Dec. 10. "If during the course of the work any evidence emerges of behaviour which is potentially a criminal offence, the matter will be referred to the police, and the cabinet office"s work may be paused," Ellis told lawmakers.