The final Portass to be developed before the firm's demise in the early 1970s was the 35/8" x 17" D5; this used the same headstock, tailstock and usefully-long 5 T-slot cross slide as late versions of the Model S but employed  a new bed and saddle. 
Unlike all previous sub-Dreadnaught-sized Portass lathes tumble reverse was fitted as standard and the apron carried proper split nuts to grip the 8 t.p.i. 5/8-inch diameter leadscrew  - though there does not seem to have been a mounting bracket to carry the essential thread-dial indicator. The changewheels were guarded by a heavy cast-iron cover with a set comprising: two 20t, and one each of: 25t, 30t, 35t, 40t, 45t, 50t, 55t, 60t and 65t.
The backgeared headstock, with its plain bronze split bearings, could (at the customer's preference), be either V or flat-belt driven (the majority appear to have chosen a V belt) and both top and cross-slide square-thread feedscrews could be fitted with micrometer dials--another first for a small Portass.
The picture below shows the D5 as manufactured during 1964 and complete with the maker's built-on countershaft unit, an assembly adapted from a bench unit used since the 1950s for the  Model S. The basic lathe, with faceplate, catchplate, changewheels and centres, was priced at £47 : 10s : 0d with the countershaft (including belts and pulleys) at £9 : 11 : 6d. To this had to be added a Burned 4-inch 3-jaw chuck at £10 : 17 : 6d and a suitable motor. A 7.5% discount was offered for cash at the factory door (or "free" extended credit terms) making a total of £62 : 17 : 6d. As a comparison, in the same year the superior Myford ML7, with the same level of equipment, was £81 : 12 : 6d - some 30% more (equal to nearly half a month's salary for a newly-qualified teacher….).