Until very recently, Paula Rego had enjoyed an extraordinary run of success since her 1988 Serpentine exhibition, the laudatory reviews keeping pace with the development of her world. Her latest exhibition, at Dulwich Picture Gallery this summer, was greeted with less enthusiasm, with one particularly intemperate critic trumpeting that ‘about a third of these pictures simply shouldn’t have been exhibited at all’. What has happened? Has Rego changed or has fashion moved on? Following the demands of her art, Rego has indeed pursued a different tack with this new work. Those who like artists to continue producing the same old stuff will be dismayed. Those who wish to see an artist grow and deepen will watch with interest.

Paula Rego was born in Lisbon, Portugal, sixty-three years ago. In the early 1950s she came to London and studied painting at the Slade with the likes of Craigie Aitchison and Euan Uglow, before marrying the painter Victor Willing and returning to Portugal. Later she divided her time (as she still does) between London and Portugal, making her main home in London from 1976, but it was not until 1981 that she had her first one-person show in the capital, at the AIR Gallery. It was a difficult time for Rego and her family, with her husband suffering from the progressive wasting of multiple sclerosis, which killed him in 1988. Ironically, it was then that Rego's own career really took off.

Her mature work draws upon the imagery of Portuguese folk tales, the great oral tradition of nursery frighteners, full of violent passions. Rego has been seen as a narrator of the human comedy refreshingly capable of putting the woman’s point of view. Her Serpentine exhibition was filled with strange, slightly surrealistic tableaux of men and women in dreamlike situations; they might have been illustrations from a compendium of psychological conditions. They were compelling and impressive, but with their static and deadpan presentation, made me yearn for a bit of movement, a bit of life. Although readily acknowledging the imaginative power (and truth) of these images, I wanted to see something that had more surface mark or paintwork in it. Some earlier pictures were included in the show, work from the 1950s and 60s, done in a mixture of oil paint and collage. These seemed to me to possess a greater physical presence than the works – mostly acrylic on paper – from the 1980s.

The new show at Dulwich consisted of sixteen pictures made around a theme chosen to suit the setting. Dulwich invited Rego to show work which might chime well with its permanent collection. Amongst all the treasures at Dulwich, the great Poussins and the Rubens drawings, Rego was particularly drawn to a couple of genre paintings by Murillo – Two Peasant Boys and a Negro Boy and Invitation to the Game of Pelota. (She loves Watteau, but there is less in the Frenchman’s oeuvre obviously in common with her work or antecedents.) The other source of inspiration for these new paintings – though done in pastel, Rego stresses they are painted not drawn – is a 19th century Portuguese novel, The Sin of Father Amaro by Eca de Queiros.

The pictures held their own well on the gallery’s walls. Rego has already done the business of working with a public collection – she was the first National Gallery Associate Artist in 1990, which resulted in an exhibition touring the country and a fine mural for the NG's restaurant. But, however oblique Rego's approach to the story of the novel, what makes these stagey scenes more than a costume drama? In many respects, a costume drama is precisely what the series is, as Rego is the first to admit. The leading question remains, does it have a contemporary relevance?

Since the Serpentine show, Paula Rego has drawn more and more from life. This research has resulted in at least two great series of pastels – Dog Woman of 1994 and Dancing Ostriches of 1995. These images speak powerfully to late 20th century Western society, but what of the Dulwich sequence? Given that it is literally drawn from real people of the 1990s, do the situations in which they find themselves belong to past or present, or to both? Are there useful parallels to be found between the age of the novel (1876) and now? The central issue in the recent criticism of Rego's work is whether the story-telling is as good as it was. Before, when she painted a cadet’s sister lacing up his shoe (1988), it was a private story which contained a public resonance. The Dulwich costume dramas Rego herself likens to dressing up dolls, and this atmosphere of charade is perhaps too pervasive.

Ultimately I don’t believe in this story because it’s not Rego's – for some reason she hasn’t inhabited it fully herself and made it her own. Her interpretation of the novel is as literal as her drawing, whereas it needs to be re-invented, re-imagined. That she is very capable of doing this with someone else’s text is evident from her brilliant interpretations of Peter Pan. Rego says she chose The Sin of Father Amaro because she felt she needed social activity rather than the stuff of folk tales. But these pictures are weighted too heavily in favour of direct observation; the story is effaced by the life-painting. If before I wanted more life in the pictures, now I’d call for more imagination. And in spite of the intense and vital working of the pastel, I’d love to see what Rego would do these days with oil paint.

Kitty North (born 1963) is a young landscape artist whose work is attracting increasing attention. The prestigious Abbot Hall Gallery in Kendal, Cumbria (where Freud showed new work and Bridget Riley will exhibit), is mounting a retrospective of her work from the last ten years. (It will run from 22 September until 1 November. An exhibition of North's current work will then be at the Swan Mead Gallery in Bermondsey, London SE1, from 10 November until 21 December.) To accompany the show I have written a monograph, which includes a full chronology, a detailed interview with North and an essay on her development.

North’s art has been nurtured by the landscape in which she grew up and the adjacent countryside of North Yorkshire where she now lives. Reading with keen interest and amusement the artist Patrick Heron (born 1920) in conversation with Martin Gayford in the catalogue published to accompany his recent Tate exhibition, I came across the following relevant quote. Heron is talking about the importance of a particular place for an artist: ‘a late 20th century painter of my generation, or even of Ben Nicholson's generation, could never see anything in Hertfordshire that would stimulate his visual imagination. You can’t imagine Christopher Wood landing up in Welwyn Garden City, or Harpenden, or somewhere, and getting cracking. You just can’t imagine it. There are certain landscapes that are immensely potent in their relationship to certain periods of art. The reason why any number of people congregated near St Ives at a certain point was because late 20th century abstract and semi-abstract painting had certain underlying rhythmic alliances with this kind of terrain.’

This is certainly true of Kitty North – the landscape has shaped her art, making it veer from a gentle pastoral naturalism to a tough semi-abstraction based upon the structures of limestone which underpin and overlay her part of the world. Her work is deepening all the time in technical assurance and in expression, and her recent interest in the Catholic church can only help to focus her fascination for the spiritual identity of the landscape. Although I am not suggesting that a whole group of artists will at once descend upon Skipton, Yorks, to found a movement like the St Ives School, it may not be simple coincidence that the sculptor Alison Wilding (born 1948) recently made a piece for Skipton Castle. There is renewed interest in landscape painting, keeping pace amongst the younger generation with curiosity about the various and varied properties of paint, that much-maligned vehicle of artistic licence. Kitty North has transmuted her responses to this particular landscape into the precious metal of fine (painted) art; there is no reason why others should not follow her lead.