Many of those are still available, even if the packings have changed!
For example, the Cup-a-Soups are now in paper sachets in a carton. The Cadbury's Cookies are more likely now in tubular foil wrappings.
Quantities are of course now metric. E.g. look at the Marmite jar - the modern one presently in my kitchen, shows the weight in grammes, and the vegan "V" symbol, on the rear label.
(Plastic milk bottles are still of pint, quart and four-pint volumes, but the label gives the volume in litre equivalents, alongside the pint amount in smaller font and brackets.)
Not sure if the Vesta ready-meals, nor a few others, are still made, though. The Lyons brand seems to have vanished, but perhaps I am not using the right shops.
