This has been on my 'to read' list for a long time, and now I've been through it, I'm thinking about the tragedy of fulfilled ambition.
This is a frustrating book. It has some wonderful ideas, some richly evocative description, and succeeds where many later writers have failed in fusing a Victorian and current (i.e. late 1980s) narrative. The influences include John Fowles (especially 'The French Lieutenant's Woman', 'The Ebony Tower', and 'The Magus' - my Picador edition has a supportive cover blurb from the older novelist), John Cowper Powys, sundry commentators on Jung, and George Eliot (the dominant influence in the re-working of the Dorothea and Casaubon strand of 'Middlemarch' which makes up the Victorian strand of the novel). The use of the Hermetic Quest as a structuring device works well (on the whole), and the novel certainly gives a strong suggestion of magical strangeness, helped by a hot Norfolk landscape (I suspect a bit of a nod to 'The Go-Between' here).
Nevertheless, I didn't enjoy the book. I appreciated and at times admired it, but I was unmoved, especially by the trials and tribulations of its modern characters. One is a drippy young poet whose wife has left him for a close friend and taken the kids (they're well off out of it). Another is the sort of intense and 'troubled' young American woman who was always having flings with older men in late-1960s films. The third member of triumvirate is a lecherous old poet, a sort of father-figure cum all-purpose mythopoeic bore, who spends his time asking pretentious and pedantic questions which are treated with far more seriousness than they deserve to be. He's the sort of man who looks at a Polo mint and says 'Do you see the mint, or the hole? Wholeness is what we lack. Ah, the moon, hanging there like a silver toenail paring dangling from a bugle. Perhaps She can illuminate our contretemps.' In short, he's the sort of man who I want to see being lowered slowly into a trash compactor, his pleas for mercy ignored.
Another reason for my lack of sympathy was the fact that the characters are always stopping to lecture one another about things they ought to know already, e.g. Tarot symbolism, key writers on esotericism, the difference between alchemists and Gnostics (yes, it's that sort of book), and so on. There is a lot of laborious symbolism, notably in the extended description of the three modern protagonists firing a pottery kiln (as the Incredible String Band might have sung, 'Earth, Water, Fire and Air / Met together in a garden fair'), and a deeply regrettable tendency for narrators (first and third person) to spend a paragraph or two brooding on something that is either patently obvious or inclined to demonstrate their lack of spiritual vision. 'Looking at her, I found I couldn't see her. She was there yet not there, existing in a liminal state of Being and Not-being that left me confused and hurt.' Is that a genuine quotation, pastiche of Clarke, or a parody? You'll have to read the novel to find out.
In the end, everything is brought together with reasonable coherence. However, for a portrait of the intelligent occult encounter, I much preferred M. John Harrison's 'The Course of the Heart'.