The colloquial British- and Irish-English nouns granny-bashing and granny-battering denote:
– the assault or mugging of elderly persons;
– abuse of an elderly member of one’s family, especially one’s grandmother.

The noun granny-bashing occurs, for example, in the following from the Evening Herald (Dublin, County Dublin, Ireland) of Friday 14^th December 2007:

Upset Irish grandchildren get insensitive tv ad pulled
By Melanie Finn
MOBILE-PHONE company Meteor has been forced to pull a controversial Christmas TV ad campaign after being accused of “granny bashing.”
Viewers were up in arms after seeing the RTE ad, which depicts an elderly granny being ejected from a family Christmas dinner because her seasonal gift of a tea-cosy does not match her host’s expectations of a mobile phone.

The earliest occurrences of the nouns granny-bashing and granny-battering that I have found are as follows, in chronological order:

1-: From a correspondence from London, by Carol Kennedy, of the Canadian Press, published in several Canadian newspapers in October 1972—for example in The Windsor Star (Windsor, Ontario) of Wednesday the 18^th:

A bizarre and frightening new phenomenon of urban violence is haunting British streets—the girl mugger.
An increasing number of assaults by teen-age girls—usually in two or threes and often from prosperous, middle-class homes—are being reported in newspapers. Police estimate there are several dozen gangs of girl muggers.
In a recent incident, a 25-year-old schoolteacher was attacked by three girls aged 16, 17 and 18 as she waited at a suburban bus stop. The girls stole her watch, tried to pull rings off her fingers, took a small amount of money and kicked her face viciously, leaving her bleeding on the sidewalk.
The 17-year-old lived in a £25,000 home in Hayes, a middle-class dormitory area on the fringes of London. Her mother, who had recently remarried, said she lived a normal life until suddenly she took to hanging around with local hippies.
In another case, two 17-year-old blondes, one armed with a flick-knife, the other with a spike, forced another girl of 17 in Croydon, Surrey, to hand over her leather jacket.
Most girl muggers concentrate on female victims, particularly the old and vulnerable. They refer to it as “granny-bashing.”

2-: From Jack O’Brian’s column Voice of Broadway, published in several U.S. newspapers in October 1972—for example in The Star-Ledger (Newark, New Jersey) of Tuesday the 24^th:

London suffers a gang of teenage girl muggers rampaging the darker Soho streets . . . Their signatures: blue jeans and switchblades. Old women are their main victims. They call it “Granny Bashing.” . . . There’s an English village named Ham in the Township of Sandwich. It’s known simply as Ham, Sandwich. Doesn’t sound kosher.

3-: From an Associated-Press report, published in several U.S. newspapers in November 1972—for example in the Las Vegas Review-Journal (Las Vegas, Nevada) of Wednesday 1^st:

LONDON (AP)—Muggers, including gangs of teen-age girls armed with switchblade knives, are undermining London’s reputation as a city with safe streets. […]
[…] Police calculate that several dozen gangs of girl muggers are operating. They specialize in attacks on elderly women, or “granny bashing.”

4-: From a correspondence from London, by Gordon Pape, of Southam News Services, published in several Canadian newspapers in November 1972—for example in the Edmonton Journal (Edmonton, Alberta) of Monday the 13^th:

LONDON—It’s still perfectly safe to go for a midnight stroll in London’s tourist-thronged west end.
But it may not be for much longer.
American-style muggings by roving gangs of youths out for cash and kicks are on the increase here, and people are getting nervous.
[…]
The muggings phenomenon has had some bizarre offshoots.
Some of the gangs consist of children as young as 11 and 12 who prey on other youngsters in their neighborhood.
Others are made up exclusively of women, who attack their victims howling like banshees.
The girls prefer to concentrate on little old ladies—“granny-bashing,” they call it—but will also take on lone men. One 50-year-old railroad worker was punched in the face and his wallet grabbed as he returned home one night; a court later sentenced two married women, both over 30 and one with four children to 2½ years each in prison.

5-: From Playing the game, by ‘Mag’, published in the Irish Farmers’ Journal (Dublin, County Dublin, Ireland) of Saturday 3^rd August 1974:

Not every sport is suitable for every child—some are team-types, some are individualists, but somewhere along the line an enjoyable one can be found. I must say I’d like to see loads of public money spent on sports facilities that would be open to all, and I do firmly believe that it would be a sensible investment for the youth of the country. The lad who is interested in playing football or swimming or sailing is not likely to be out “granny bashing” or smashing up homes and furniture.

6-: From Tolerance of Debility in Elderly Dependants by Supporters at Home: Its Significance for Hospital Practice, by J. R. A. Sanford, M.B., M.R.C.P., Senior Registrar, published in the British Medical Journal of Saturday 23^rd August 1975:

Some 12% of all geriatric admissions to University College Hospital and Whittington Hospital are for patients whose relatives or friends can no longer cope with them at home. The person principally involved with home support was interviewed in 50 such cases. The causes of inability to cope were identified on a quantitative and qualitative basis. The supporters were asked to assess which of the problems identified would have to be alleviated to restore a tolerable situation at home; 46 (92%) were able to do so. Identification of the “alleviation factors” forms a therapeutic and prognostic guideline in this type of admission and may have far-reaching social and economic implications.
[…]
Most of the problems the supporters felt unable to cope with in future home management—the “alleviation factors”—fell into group 1 (80%). In this group the most frequent problem was sleep disturbance (62% of cases), in which the supporter was woken regularly at night by the dependant for various reasons. This was poorly tolerated (16%). This may not be the only type of dependant relationship in which sleep disturbance causes stress; for example, it may be a factor in the battered baby syndrome. Despite the fact that sleep disturbance generated much animosity in the supporters, however, no evidence of “granny battering” was found.

7-: From the following letter, published in the British Medical Journal of Saturday 6^th September 1975:

Granny-battering

Sir,—Hardly a week goes by without some reference in the national press or medical journals to baby-battering, and I think it is about time that all of us realized that elderly people too are at times deliberately battered. I have personal knowledge of cases in which it has been possible to confirm that elderly patients have been battered by relatives before admission to hospital and in which there has been no doubt that the battering was deliberate. In other cases assault at home has been suspected but could not be confirmed. This leads one to wonder how many of the elderly who “fall down frequently, doctor” do so because they are assaulted.
Often the type of patient in whom the suspicion of battering must be very high has some mental impairment. While in no way condoning the battering of elderly people by their relatives, I am certain it is just another manifestation of the inadequate care we as a profession give to elderly people and to their relatives who are left with the task of coping with them unaided and unsupported by us. It is hardly surprising under these circumstances that the battering becomes almost a natural consequence of the inadequate service. Perhaps general practitioners in particular and casualty officers especially should become as conscious of granny-battering as they are now aware of baby-battering. Community nurses, health visitors, and social workers should also have this aspect of “caring for the elderly” drawn to their attention.—I am, etc.,
G. R. BURSTON
Southmead Hospital,
Bristol