I think I have found them Pat.There were 4 regularly used.
First,see the following site HERE.
Then some additional material :
EMPIRE WANSBECK, (with VIENNA, ANTWERP and EMPIRE PARKESTON,) made up that group of small regular troopships which operated across the North Sea, the need for which was created by the establishment of BAOR and RAFG.
EMPIRE WANSBECK was also one of the units of the post-war trooping fleet which was acquired as a war prize.
In 1939 a twin screw motorship was laid down at Odense for the Norddeutscher Lloyd of Bremen. She was launched in 1940 and named LINZ. Completion was delayed until 1943 when the vessel was put into service with the Kreigsmarine as an auxiliary minelayer. LINZ was a vessel of 3,374 gross tons with a length overall of 336'5", a maximum breadth of 45'8", and a speed of 15 knots.
She was sent from Copenhagen in May of 1945 in the attempt to rescue Germans in the eastern territories from the path of the advancing
Russians. Two months later, on the 8th July, she was back in Denmark and became a British prize. She was taken over by the government and converted into a troopship with the new name of EMPIRE WANSBECK. Ellerman's Wilson Line was appointed to manage her on the trooping run from Harwich to the Hook of Holland on which she operated until the end of cross-channel sea trooping in 1961.
On retirement from trooping, the ship was sold to the Kavounides Shipping Company of Piraeus who renamed her ESPEROS. She was employed in the Mediterranean, mostly cruising among the Greek islands, at least until 1967. By the 1st March 1975, however, her owners reported that she was "idle in Piraeus" so that her future would seem to be a little uncertain. [She was broken up at Gandia in March 1980.]
EMPIRE PARKESTON (6,893 tons)-Ex- Prince Henry, 1946 purchased from Canadian Government and renamed Empire Parkeston. Feb.1962 scrapped at La Spezia.
MEMORIES - "SNIPPETS" OF A RAMC MEDICAL ORDERLY - Graham Hibbert
There are two troop ships that you hear very little about, the Empire Parkeston and the EmpireWansbeck, these were known as ST's (sick tubs).
They operated a a night crossing several times a week from Harwich to the Hook of Holland (for onward rail transport to Germany) and return.
Medical staff consisted of two RAMC lance-corporals only, provided by Netley on secondment to movement control Parkston Quay Harwich, I spent several winter months on these ships; we had a small medical room and were always busy. For serious incidents we were totally reliant on any doctors and QA's in transit and radio advice.
Unfortunately I do not have any photos, at the time these ships did not have the sense of adventure and excitement as deep sea trooping. - Graham Hibbert.
S.S.ANTWERP 2,957 tons.Built 1920 by John Brown’s,Clydebank.for Great Eastern Railway.
Sister to MALINES and BRUGES. On trooping duties from Southampton to Cherbourg from January 1940. In June 1940 she took part in the evacuations from Cherbourg, St. Malo and Guernsey to Southampton and Weymouth.
Commissioned into the Royal Navy as H.M.S. ANTWERP in November 1940, in October 1941 she sailed to the Mediterranean via the Cape, being based at Alexandria as a convoy escort and as a troopship. In March 1943 she was converted to a fighter direction and forward operations ship, and in this role carried Admiral Sir Bertram Ramsay and Admiral Lord Louis Mountbatten to the landings in Sicily in July 1943. During the rest of the war she served variously as an air-sea rescue ship, convoy escort, troopship and fighter direction ship.
Arriving back at Plymouth in March 1945, she was returned to LNER ownership but did not resume commercial service. She was refitted as a troopship and entered service from Harwich to Hook of Holland in this role in September 1945. This lasted until she was sold for breaking at Milford Haven, arriving there on 4 May 1951.
S.S.VIENNA Built 1929 by John Brown,Clydebank London & NE Railway. 4,218 tons
Scrapped at Ghent May 1960.
Picture of ANTWERP which is not included in the link above (for completeness).