THE weighty blanket of grief still shrouds Elizabeth MacLennan's days and nights. It's only a few short months since her husband and lover and comrade in arms, the radical thinker, author, and playwright John McGrath, died, but here she is preparing to celebrate her man's life and work with one hell of a party.

It's the fulfilment of a promise she made after a form of leukaemia cruelly robbed us of McGrath's generous spirit and brilliantly passionate intellect at the tragically early age of 66 last January.

The day after McGrath's death in London we were talking on the phone and MacLennan said softly, her gentle voice full of tears: ''I am going to come home and throw a huge party for John - and it'll be a party the like of which Edinburgh's never seen.''

The McGraths were justifiably famous for their ceilidhs - both on stage and off - so it's fitting that A Good Night Out, in memory of the man who dramatically changed the face of British theatre forever, in Edinburgh this weekend, should take the form of a carnival.

The damson-haired, beautiful Glasgow-born actress and writer, for whom McGrath created so many memorable roles, and their 22-year-old daughter, Kate, have put together an evening of songs, poems, short speeches, and scenes from his many plays, plus clips from his film and TV productions - to be followed by a ceilidh and dancing.

The performers, who will be birlin' into the wee small hours, include some of McGrath's closest friends and colleagues. Many are famous names and faces, who remember the tall, handsome, leonine founder of the 7:84 Theatre Company with enormous affection for his huge talent, the limitless depths of his humanity, and for giving them a start in the business.

They range from the film and stage actor Jonathan Pryce (who is about to finish a long run in the National Theatre's West End production of My Fair Lady), to Trainspotting's Kevin McKidd, as well as Stephen Rae, Gerda Stevenson, and Catherine-Ann MacPhee. John Bett and Bill Paterson, who were both in the original production of The Cheviot, the Stag and the Black, Black Oil, will be there, too.

There are many others too numerous to mention here, but MacLennan agrees: ''It's quite a line-up!'' She will, of course, also be appearing, singing in the chorus, holding the song sheets - ''and I might just flit by with some curlers in my hair''.

The couple were life-long collaborators, producing not only two sons, Finn and Danny, and their daughter, but a whole raft of fine work together. Just two days before he died, she sat at his bedside in London watching him correct the final proofs of his last book, the acclaimed Naked Thoughts, which was published last month.

Twenty-four hours before his death, MacLennan wrote the chronology of her husband's work for the index of that book. When she sees his achievements listed, yes, she mourns the extinguishing of a bright talent, but she is also filled with gratitude that he brought so much joy to so many, that he could so effortlessly make audiences laugh as well as think.

''In the wake of John's death, we all have a lot of reasons to be sad - and none more so than me - but A Good Night Out is not going to be a sentimental occasion and it most definitely will not be sombre or melancholy. It'll be a great big show, with lots of fun, the sort of evening that he hopefully would have been immensely proud of,'' says MacLennan, who is looking as striking as ever after a six-day break in Greece, from which she has returned tanned and rested.

''I was exhausted because I have literally been going flat out since John died,'' she admits. There was the book to get out, A Good Night Out to devise and organise, and then she and her daughter decided to stage a full production of his final play, HyperLynx, first seen in a rehearsed reading at the Edinburgh Fringe last year. He wrote the one-hour, one-act play especially for his wife and she will appear in the Floodtide version.

HyperLynx was performed last year alongside a new piece by MacLennan herself, Wild Raspberries. The two will play at the Citizens' Theatre in Glasgow later this month. The Floodtide company was started by Kate McGrath and a group of like-minded, fellow students at Cambridge University (from which she gained a first class honours degree last year).

''I like their work,'' says MacLennan, who has been a devoted fan since their earliest appearances on the Edinburgh Fringe several years ago. ''I'm interested in what they stand for and, above all, I admire their commitment, as did John. I find Kate, as a director, is completely without ego, which is very refreshing.'' Both plays will run at the Pleasance during the Edinburgh Fringe in August.

Kate McGrath will direct HyperLynx, which her father re-wrote in November in light of the events of September 11 in New York. ''It's an extraordinary piece, written with enormous clarity like all John's work,'' says MacLennan, adding that despite being finished months before the attacks on the World Trade Centre, it uncannily prefigures the atrocity.

The first version, which in that rehearsed reading revealed that McGrath had lost none of his anger or his burning desire to make the political personal, was written while he was hospitalised last summer. Sitting by his bed for hours on end, MacLennan wrote her play, Wild Raspberries, a deeply-felt story about ageing, told through the voices of three women. Hospital staff were forever asking: ''Do you two never stop writing and reading, reading and writing?''

Of course the answer was in the negative. ''The doctors and nurses didn't know what to make of us. We were either writing or talking. We never stopped communicating with each other, as well as with our audiences.'' As MacLennan points out, she and McGrath started talking more than 40 years ago when she was still a student at Oxford University.

''I was 20 when I first had a conversation with John - and I'm not about to stop now. Just because I've been deprived of his company I feel I shouldn't be deprived of his words. I find great comfort in them. I intend to go reading and performing them as long as I can because it's my way of talking to him. In fact, while I've been rehearsing HyperLynx, once or twice I've said out loud, ''Now, John, what exactly did you mean there? Can you just elucidate that wee sentence for me?'' Usually, she knows the answer before she asks the question, because they were always each other's sounding board when making new work.

She has, of course, many wonderful memories to draw on of the lifetime she and McGrath lived, loved, and laughed together. Even when he was so stoically fighting the illness that killed him he was irrepressible, enjoying every moment of his life. They spent Hogmanay, 2001, for instance, dancing in the streets together. ''I'll never forget that,'' says MacLennan, laughing happily at the recollection.

They also shared a marvellous Fringe last August. Looking like a tired, balding eagle, McGrath was stooped and weary after a spell in hospital, but he saw dozens of shows. I went to one production, The King Lear Project, with them at which the three of us were the only audience members. ''Wasn't that fun!'' recalls MacLennan. ''How John laughed - it was such an archetypal Fringe experience.''

At the Traverse, McGrath, patently weakened physically by his illness, spoke fluently and movingly in a debate with Scotland's young theatrical turks about how class still defines the ways in which theatre is perceived. ''Oh, that was quite a day!'' says MacLennan. ''You could just see them all thinking, 'Oh no, it's the old lion himself!' as he walked in. But didn't he just make them sit up and listen!''

One thing is guaranteed - audiences for A Good Night Out, the proceeds of which go to leukaemia research in Scotland, will also sit up and listen - and they'll almost certainly go away with a song in their hearts. Looking back through his work to compile the show, MacLennan was struck by the extent to which music and lyrics were so central to his artistic endeavours.

She hopes that the rising young star Kevin McKidd - who like many

others got his first stage role with

7:84 - will sing a number from one

of McGrath's great unperformed works, the musical Greenbreeks, about the young Sir Walter Scott

and his uneasy relationship with the Edinburgh establishment.

''It will be the first time it's ever been performed in public,'' says MacLennan, adding that a truly lasting memorial for her beloved husband would be a full-blown production

of the work. ''I think what Greenbreeks - and all John's other work

- proves is that he never wasted a minute of his life, and I'm most certainly not going to waste a second of what's left of mine.''

A Good Night Out is at the Assembly Rooms, George Street, Edinburgh, on Sunday.

Tickets (pounds) 10, concessions (pounds) 5. Telephone 0131 220 4349. Wild Raspberries is at the Citizens' Theatre, Glasgow, May 28 and 29; HyperLynx, May 30 and June 1.

Naked Thoughts That Roam

About is reviewed in tomorrow's Living section.