For every secretary who has fractured a fingernail on her pinkie while lunging for the Q key, Lillian Malt's electronic typewriter keyboard will be as welcome as a holiday bonus.

It is called MALTRON in honor of its inventor, and its concave plastic keyboard features keys set at varying heights to fit the differing lengths and strengths of the fingers. (The thumbs, underutilized on the conventional keyboard, are given up to eight keys each.) The instrument also includes a radically reshuffled alphabet that places the most commonly used letters directly under the fingers, on the so-called "home row." "It's so lovely," gushes one admirer, "I could rest my head on it."

The portable keyboard, which Malt says a typist can master in four weeks, weighs only three pounds and can be plugged into a converted electric typewriter. A secretary will be able to prop the keyboard on her lap for dictation in her boss's office, typing directly into her deskbound machine. The first MALTRONs will cost $850 apiece and will be marketed in Britain this summer. American distributors will be licensed later.

Trim, attractive and 60ish, Malt is a third-generation South African (staunchly antiapartheid) who immigrated to Britain 22 years ago. Trained as a commercial teacher and more recently a designer of computer training systems, she has devoted much of the last 15 years to pondering such things as keyboards, typing errors and the physiology of fingers.

A childless divorcée, Mrs. Malt works alone in her spacious two-story home in Surrey, where she is able to indulge her passions for gardening and horseback riding. She is also involved in a charitable trust which aids children with learning disabilities.

First and foremost, however, she puts in long hours refining her theories. "It's hard work inventing," Mrs. Malt observes. "These ideas don't come to me in my dreams."