It's worth have a hunt through that bbc catalogue for other star wars related gems - no sign of the Michel Parbot or the Making of ESB doc, unfortunately. No real suprise there, as I don't think anyone was expecting it to be a BBC programme.

Here's a few more I've uncovered:

A 1977 edition of Blue Peter
ITEM 03:STAR WARS:Mark HAMILL joins John & Lesley wearing a Star Wars helmet in the studio, includes cpyrt clip of Star Wars.
http://open.bbc.co.uk/catalogue/infax/programme/LCH9488Y

ARENA (1978)
CINEMA, THE FORCE IS WITH US?:HOWARD HAWKS
# Star Wars - Howard Hawks
Gavin MILLAR pres mag prog on the cinema with items on the phenomenal success of "Star Wars"; & an intv with dir Howard HAWKS, filmed shortly before his death.
extra details
# STAR WARS: (0.2-10.26) This film is now the worlds biggest movie, it has cost 9.5million dollars & grossed over 200million dollars in the USA alone. It had a film crew of 900 & four million dollars was spent on special effects. GAVIN MILLER intvs producer GARY KURTZ & actor MARK HAMILL in London & they speak about the story & the filming. JOHN BARRY with designer speaks on howt the robots wre made, var s GAVIN MILLAR with models of actors & robots (0.2-0.58) SIR ALEC GUINNESS & GEORGE LUCAS director with technicians & robots on the set (0.58-1.38) it workshop (10.08-10.27) vars thruout of filming in Tunisia on location.
http://open.bbc.co.uk/catalogue/infax/programme/LMA1670F

and I think someone - was it you Jambe? - mentioned this one previously

THE RISK BUSINESS
THE MOVIE
* A television programme
* BBC Programme Number: LSFE030X
* First broadcast on 1980-04-09
* Media: FILM
* Next in series: MR CUBE FIGHTS BACK
* Previous in series: WHATEVER HAPPENED TO...?
* See more THE RISK BUSINESS programmes (48)

Seq 1 : Michael Rodd at Elstree studios on set of 'Star Wars' sequel 'The Empire Strikes Back'
(0-2.59); comments from actors HARRISON FORD, ANTHONY DANIELS & MARK HAMILL (0.59-1.25),producer
GARY KURTZ (1.25-1.44) & director IRVIN KERSHNER (1.44-2.05) on working with British technicians in UK. http://open.bbc.co.uk/catalogue/infax/programme/LSFE030X

TONIGHT
15 November 1977
# Barry Norman intvs. Kurtz producer of Star Wars.
# Subjects covered; How Stars Wars was originally set up; Reasons for the film's enormous appeal....i.e. traditional John Wayne type heroes; The use of British technicians for the special effects; Work already being done on the sequel.http://open.bbc.co.uk/catalogue/infax/programme/LCA1829T_B

There's also this radio programme, which would be great to hear, and valuable addition to Jambe's Star Wars Project.
KALEIDOSCOPE
22 December 1977
# SBH:Sir Alec GUINNESS, actor, interviewed on his role in the film "Star Wars".:Interviewer: Paul Gambaccini. From Kaleidoscope
# PRE: Difficulties in playing magical role; interpretation of same; people believed character was real & got letters to prove this; would like to appear in another "Star Wars" film TXN/TDT:R4 22-Dec-1977 CON:GUINNESS Alec, Sir (spkr) GAMBACCINI Paul (int) Complete programme now available on T 98620.
http://open.bbc.co.uk/catalogue/infax/programme/SX+13624_4
EDIT - found it online - very brief but worth it. Just listen for his pronunciation of Jedi Knight: http://news.bbc.co.uk/1/hi/entertainment/869896.stm

I'm sure there's lots of other stuff in the catalogue waiting to be uncovered, although a lot of it will likely be a mixed bag of chat show appearances and movie review shows.

Apologies to digialfreaknyc for turning this thread into an 'other rare gems' thread.