Mr Hull is a former meteorologist at the London Weather Centre and his wife a retired head of English at King Alfred School, Hampstead, north London, an experience that does not seem to have spoilt her taste for the curdled witticims of generations of dairymen.
The two offerings above are by Clyde Higgs, a dairyman in Leamington Spa up to the Sixties, whose efforts as a wordsmith merit comparison with those of William McGonagall, the immortal Victorian poetaster. Higgs also dreamt up the expression: 'Your cat miaows at milk from our cows.'
Such a man, one imagines, might empty public houses on sight. ('The milk's thine, / The bottle's mine' is his, too.) But Mr and Mrs Hull have received no reply to their letter to a close relative of Mr Higgs, asking for biographical details and a list of his literary efforts.
The motherly, mythic status of milk - 'land of milk and honey', 'milk of human kindness' - might be responsible for the awkward, often macho slogans on bottles and the bucolic imagery.
Mrs Hull is now an authority on artwork that specialises in smocked yokels, soppy milkmaids and a variety of dancing cows.
Milkmaids in short skirts and bonnets decorate this quatrain printed on a Sixties bottle for O Tomlinson's dairy in Ashbourne, Derbyshire: ' 'Where are you going to, my pretty maid?' / 'To Church Fields Dairy, Sir,' she said. / 'It's tuberculin tested milk,' he said. / 'That's why I'm going, kind Sir,' she said.'
The proverbial sexual opportunism of milkmen is celebrated in the Seventies bottle slogan accompanying a picture of a comely housewife putting empties on her doorstep: 'Didn't she do well]'
The bulk of the collection, according to Mrs Hull, 'has come from crawling around in undignified positions'. In Stockton Wood, on the A303 in Wiltshire, she and Mr Hull scavenged bottles bearing the names of more than 300 different dairies, all lying within throwing distance of the road where generations of picnic-makers had parked their cars.
Printed slogans are already a thing of the past - the print hinders production-line scanners seeking foreign bodies in the milk. And the glass bottles themselves, preferred for doorstep deliveries, are an endangered species: the number of dairies delivering in the Greater London area, for example, has dropped from more than 1,000 in 1931 to fewer than 10 today.
But milk bottles have yet to fetch crazy collectors' prices. Pre-war bottles change hands at collectors' charity auctions for pounds 2- pounds 3 each, or pounds 15 a dozen.
However, Mr Hull paid pounds 30 for a Fifties three-colour bottle salesman's sample, the only one known from the Co-op Glass Manufacturing Company, and dollars 200 (pounds 130) for a 1984 Thatcher Milk Protector with spring-loaded cap from an American collectors' catalogue. He reckons that his collection, if offered at pounds 1 a bottle, would not be absorbed by the country's 100 collectors. 'You can't get rich collecting milk bottles,' he said.
For budding milk-bottle buffs: factory production of milk bottles began in Britain in the 1880s, gradually superseding street sales from churns. Before 1910, bottles were made from light-green 'aqua' glass (clear glass was taxed) which made the milk look awful.
Foil caps date from about 1930. Internal cardboard seals were phased out as a result of the 1950 Hygiene Act. Wartime cardboard seals bearing such slogans as 'Wasted waste is wicked waste' are highly collectable.
You can still come across old bottles containing drinkable sterilised milk. Some survived the Blitz. A bottle with 'milk' moulded on it, recovered from a shipwreck off Plymouth, dates from 1856 and would have contained sterilised milk.
Most of the Hulls' collection is from the Thirties, when advertising on milk bottles flourished. The bottles even carried advertisements for cigarettes. Milk-bottle ads fell out of favour after the war but resumed in the Seventies with promotions for toothpaste and British Rail. Collecting tip: look for rare pre-war Disney designs. What price the bottle with the slogan, 'Mickey Mouse is always gay, / He drinks two pints of milk a day'?
The Hulls publish a quarterly journal, Milk Bottle News, annual subscription pounds 6 (0453 884922).