Home Office figures showed 737 people made the journey to Britain via small boats on 13 December across 11 vessels - an average of 67 people per vessel.
The operation involved a specialist Merlin helicopter from 814 Naval Air Squadron and RFA Tidesurge - a replenishment tanker which is part of the Royal Fleet Auxiliary.
According to officials, UK patrol vessel HMS Severn shadowed the Russian corvette RFN Stoikiy and the tanker Yelnya over the past two weeks as they made their way through the busy shipping lane.
The alarm was raised when a French-coded radio beacon was activated in the middle of the night in April last year about 40 miles off the coast of Land's End in Cornwall.
A Royal Navy destroyer and helicopter were deployed on a 48 hour NATO operation monitoring a Russian warship in UK waters, marking a historic first for the alliance.