SOME words and phrases connected with food have the power to propel us backwards in time. Talk of hostess trolleys and pate maison and you place yourself in the era of 1950s and 1960s dining chic, writes John Edmonstone.

Another such phrase, in Scotland at least, is ''high tea'' - two words evocative of an era of starched linen and lace aprons. High tea is a meal peculiarly Scottish, which now seems consigned to culinary history. What was it, though, that once made it so popular?

High tea is an odd meal, when you think about it. The menu contains bread cakes, scones, or teabread. The centrepiece is a plain but substantial main course, perhaps bacon and eggs, or haddock and chips, but it's nowhere near as formal as dinner, and rarely offers vegetables, other than peas or salad.

Its roots lie in Scotland's economic and social history. The urban poor in the nineteenth century came to see the evening meal built around two staples - bread and tea - because they were cheap and available to all, and because tea was safer to drink than water and more moral than beer.

In rural communities tea had to be a substantial meal. The main meal of the day, dinner, was taken at midday, but in the harvest months workers needed something to sustain them into the evening. So, take the baking the farming wife prided herself on, fine but simple, add to it home-cured bacon, eggs, kippered or fried fish, and you had an elevated tea - high tea.

And, as Scotland's urban poor increased in prosperity, so their evening meal became more elaborate, basic bread and jam and tea supplemented by shop-bought cakes and scones, tinned meat, or bacon from the grocers.

But it was the invention of the tea room and the growth of an urban middle-class that pushed the high tea into prominence. Glasgow invented the tea shop, or at least Stuart Cranston, tea-dealer and founder of the Cranston tea shops, did. The city's growing merchant class provided a custom for the new establishments. It was a place frequented by men - clerks, office workers, bosses alike - dining without temptation of drink. With the strength of the temperance movement in the early part of this century that was an important influence. The tea rooms provided the perfect environment and the high tea menu was usually offered from around 3pm to 7pm.

An establishment such as Miss Cranston's offered among the items on its menu, in 1917, cold Tay salmon and salad for 1/1d; kippered herring for 5d; cold roast lamb for 1d; or bacon, sausage and eggs for 1/-; all available with tea, toast, bread, scones and ''bakes various''.

But for the travel writer, H V Morton, in 1929, the institution of high tea seemed alien, ''the astonishing meal of high tea which Glasgow's cafes and restaurants have elevated to the apex of the world's pyramid of indigestibility (for I still cannot believe that tea agrees with

fillet steak).'' None the less the city thrived on it.

In her history of the Glasgow tea room Perlita Kinchin lists nearly 350 establishments to be found at one time or another in the city centre. The names are evocative of another age - Linda's Tea Rooms, Lockhart's Cocoa Rooms, The Bungalow Tea Rooms, Wendy's. From the thirties to the fifties it was the golden age of the high tea.

What killed it off was the growth of the restaurant trade, and, if one famous Glasgow name, Cranston, was at the birth, another - Stakis - was at the death. The restaurant empire Reo Stakis built up was founded in a new era, with a desire for sophistication. It might be said the fifties and sixties boom in the steak-house phenomenon was laid on the ashes of the tea room. In some cases many of Stakis's chain of restaurants were located in former tea shop premises. An evening meal offered a veneer of sophistication, most especially in the replacement of the pot of tea with a bottle of Spanish plonk. The classic formula of prawn cocktail, steak, and black forest gateau became the high tea of the sixties.

Tastes and fashions have changed and the high tea has all but disappeared. But not entirely. It is still possible to find some establishments serving high tea. The world-famous Nardini's cafe and restaurant, in Largs, is one such place. For #6.80, between 4-7pm you can choose from a menu including grilled wild salmon steak, bacon and egg, fried haddock, pizza, lasagne, omelette, and, of course, the obligatory tea, toast, cake or teabread.

Fabrizio Nardini, the third generation of his family to run Nardini's since his grandfather came to Scotland in 1890, says: ''There's definitely a market for high teas. It tends to be most popular with our older clientele and families. It is the traditional items we offer - the fish and steaks and grills, and of course scones and cakes. Scots still have a very sweet tooth.''

The years after the war were the heyday for this trade, for establishments like Nardini's. ''We built up trade from small beginnings,'' says Fabrizio. ''In those days dishes like bacon and eggs were very popular.

''In the sixties we began to move into dinners, but we kept the high tea menu going, whereas a lot of the hotels gave up.

''Nowadays customers can order a glass of wine with the menu, if they want to, which certainly wasn't something you did in the past. We offer a more modern and varied menu in our restaurants, everything from oysters to a steak pie.

''We try to balance the two things - keeping with tradition, and moving with the times. But as far as the high teas go, I can't foresee a time when we won't be doing those - as long as people want them.''