It will hardly do. Wheatley was at the very least conservative, and I would happily claim him as a reactionary with only slight reservations.
In particular, he had no respect for mass democracy. His letter (available in full as an 11-page pdf from the BBC) disposes of it in a couple of paragraphs:
... But the voice [of the people] was stilled by the coming of the electro-machine age, as the new inventions enabled the professional politicians of all parties to get into direct touch with every community, however remote. First came the electric press, enabling a million or more copies of a newspaper to be run off in a single night -- and enormously improved arrangements for distribution. Then came the wireless telegraph -- which swiftly developed into radio, with a five times a day news service which, by means of a cheap receiving set, could be picked up in every home. And these were followed by the cinematograph which soon became one of the most insidious weapons for political propaganda.
The result was that instead of forming their opinions by quiet thought and reasoned discussion, the bulk of the people took them ready made (from so called "informed" sources) ...
And before you ask, no, blogging doesn't help. What led to the centralisation of opinion-forming was not the necessity of centralisation - such as has been attributed to the capital costs of printing and broadcasting - but the possibility of centralisation: the fact that the most immediately attractive ideas could reach everyone at once, unfiltered, and gain credibility from their momentum.
(Do not imagine that I wish to reimpose the filters on the flow of ideas: it can't be done, and it shouldn't be done. I don't want to control the opinions of the masses, I want to ignore them.)
So, no, Ian, Wheatley would not think all the better of us for being "committed to peaceful change through the ballot box". He would think we are wasting our time.
Unfortunately, his prescriptions are not optimistic, unless you accept his assertion that when we are killed fighting for our freedom against the state, we will be reborn with "a finer, stronger personality" as well as being an example to others. (The problems of being an atheist and a reactionary are a subject I've been meaning to write about for a while).
Back to Wheatley's non-libertarianism; if we have any historical model of libertarian government, it is probably Whig Britain at the end of the 19th century. Here's what Wheatley's recurring hero the Duke de Richleau says about the classical liberal movement, in a scene set in 1906
The main plank in the Liberal platform has for long been Free Trade, and with it they have won the votes of the masses in the towns because, on the face of it, their policy means cheap living. But go a little deeper into the matter and you will find that it has another altogether different aspect. The great strength of the Liberal party lies in the industrial north, and the money to finance industry comes from the rich manufacturers and the old Whig families who have invested their wealth in commerce. They are very shrewd people, and they know that if they can bring the cost of living down they will then be able to force down wages and derive bigger profits from their factories.
"Vendetta in Spain", Dennis Wheatley, 1957 ISBN 0-09-004660-9 p.153
I mentioned slight reservations about Wheatley's reaction - simply, he is too soft. In the letter, he defends Kings being answerable to an aristocratic class, and even to the will of the people when that was not short-circuited by mass communication.