Although Operation Dynamo at Dunkirk had evacuated much of the fighting element of the BEF, some combat units from 1st Armd Div, & Beauman Div and more than 150,000 support and line-of-communication troops had been cut-off to the south by the German “dash to the sea” In addition, the 52nd (Low Div) and the 1st Canadian Div had been rushed to France to bolster the defence of the west of the country. General Sir Alan Brooke was returned from England to command them. Upon his arrival on 13th June, he quickly realised that there was no chance of success for them and that the French plan to fall back and make a stand in Brittany was unrealistic. Accordingly, in a telephone call on the evening of 14th June, he was able to persuade the British Prime Minister, Winston Churchill, that all the British troops in France ought to be evacuated.
Evacuation from, St Nazaire
The evacuation from the more westerly ports was commanded by Admiral Sir Martin Eric Nasmith, the Commander-in-Chief of the Western Approaches Command based in Devonport.
Waiting at St Nazaire were a large number of British Army units, RAF personnel, Allied troops as well as British civilians.
The flotilla sent included the large troopships Georgic, Duchess of York, Franconia, RMS Lancastria and Oronsay. The Franconia was damaged by bombs en route and returned to Plymouth. Most of the larger ships had to anchor in Quiberon Bay because of the difficulty of navigating the narrow channel up the Loire estuary to St Nazaire. During 17 June, troops were ferried out from St Nazaire to the large troopships in destroyers and coasters. The troopships were under orders to embark as many personnel as possible and soon became very crowded. At 2pm there was an air raid by German bombers and the Oronsay was hit by a bomb on the bridge. In a second raid, HMT. Lancastria was struck by a salve of four Bombs about 15:45hrs GMT 17th of June 1940.
The ship had embarked with over 5200 troops and refugees, including women and children, the wind was light North West,slight sea swell, cloudy with bright periods. The ship sank rapidly by the head listing from side to side, a bout 10min after being hit at 16:00 hrs, the ship heeled over on her port side and sank, the ship sank within 3 to 4 miles distance of the shore, but the ship was surrounded by a large quantity of oil which was a great handicap to any of the survivors trying to swim away from the sinking.
After the air attack had subsided about 4.30 pm, many vessels – destroyers, tugs and smaller craft, both French and British – came to the rescue of survivors. The trawler HMS Cambridgeshire was first on the scene and was able to rescue between 800 and 900 survivors, all taken from the water most of those rescued were taken to Plymouth, the destroyers HMS Beagle taking 600 and HMS Havelock taking 460; the cargo ship John Holt took 829; the tanker Cymbula took 252 and the liner Oronsay 1557. Lesser numbers were brought back in other ships which are commemorated in a panel in 'Lancastria’s Church', St Katharine Cree, in the City of London.
Amongst the survivors were 3 members of the Manchester Regiment:-
3532687 Lcpl Heslam J.W. (WO361/5/1 War Casualties on Lancastria)
3532682 Pte Booth A. (WO361/5/1 War Casualties on Lancastria)
3532640 Pte Balfreyman R. (WO361/5/1 War Casualties on Lancastria)
Source
HMT Lancastria Association http://www.lancastria-association.org.uk/index.php?page=history
Wikipedia ( operation aerial)
Official history of the Second World War (Book)
Google maps