My old chum Nigel Thornton has provided me with this. While the Deal was not a ferry she did carry general rail cargo on the cross-channel route.
Steel twin screw steamer, built and engined by D. & W. Henderson, Glasgow, in 1927 (Yard No 818) for the Southern Railway. Launched February 10th 1928. 
DIMENSIONS: 
Length on deck - 69.82m (229.06 ft) 
Breadth of hull - 10.24m (33.6 ft) 
Depth - 4.30m (14.1 ft) 
Tonnage - 687 gross (1928)(691, 1939)(787,1941)(829, 1946) 
270 net (1928)(270,1939)(289,1941)(310,1946) 
Engines - Two Self-Reduction 6-cylinder steam turbines 
Power - 1,850 ihp 
Speed - 15 knots 
Capacity - 0 passengers, 30,000 cu ft of cargo space 
Sister ships: T.S.S. TONBRIDGE, MINSTER, HYTHE II, WHITSTABLE, FRATTON, 
MAIDSTONE II, + HASLEMERE 
and RINGWOOD. 
From 1924 to 1928 nine new twin-screw cargo steamers were put into commission on the Dover, Folkestone and Southampton services by the new Company (Southern Railway); the above seven were allocated to Dover and Folkestone, the remainder being based at Southampton, though a certain amount of interchanging has occurred from time to time. These ships were all alike though their gross tonnage varied between 680 and 750; they came from Meadowside Yard of Messrs. D & W Henderson, Glasgow, the firm so closely identified with the old Anchor Line. They were handsome ships of their class, each with a single funnel, two masts and cruiser stern. They appear to be credited with a maximum speed of 15 knots. 
Deal
February 10th 1928: Launched at a cost of £41,810. 
April 27th 1928: Holed on rocks off Ireland during her delivery voyage. Re-floated after 4 hours and returned to her builders. Based at Dover/Folkestone.
1935: First went to the Channel Islands to provide extra cargo capacity at the height of the produce season 
1940: During World War II DEAL was held in readiness. 
June - July 1940: Assisted with the evacuation of the Channel Islands military equipment. 
June 16th 1940: Came out of St Malo with troops. Based Weymouth (the civilian clearing station). Took the military stores into Plymouth. Served as a Barrage balloon vessel, based at Sheerness until 1943. 
November 1943: Served Fishguard - Cork. 
1944: Manchester (later Heysham) - Belfast weekly service. 
June 25th 1945: Returned to her owners. 
July 3rd 1945: She was one of the first Southern Railway vessels on the Channel Islands service after their liberation. 
November 1945: Completed Channel Islands service and returned to Folkestone 
January 1st 1948: Came under the sole possession of Southern Region of British Railways
May (end)1960 - June (beginning) 1960: Reappeared on the Channel Islands service, she made a few trips. 
1963: Sold for scrap. 
May 25th 1963: Arrived at Ghent for breaking.