It seems odd to me that you're satisfied with the control of your palm and sole psoriasis, which is hard to control, and unhappy with facial sevorrhea, which should be quite easy to control.
Any number of mild topical steroids should be able to suppress facial involvement to the point of invisibility. Non-steroidal creams like tacrolimus or pimecrolimus (not sure of trade names in UK) may well do likewise. Nothing cures the condition, of course, but you should be able to walk around without anyone knowing you have it.
I advise you to ask your dermatology consultant about this.
Best.
Dr. Rockoff
other creams: Cutiax, tea tree cream biocare, MSM lotion, E45, Savlon,etc... Currently waiting for delivery of biolayn cartilage cream
sorry once last point which I'm sure will be off value to many. I see you advise the use of 1% hydrocortisone for facial seb derm yet on the tubes they advise against this. I guess this is becasue the skin is thinner on the face and atrophy is more probable. How long should this be used on face and how long between courses to avoid such a thing? Great site by the way!