Living abroad. What to do with inherited Irish shares?

Some shares have just surfaced in a bank deposit box (625 in Jurys Hotel Group, 330 in Irish Permanent) during the dispersal of my late mother's estate which like the rest of the estate (which totals well below level for CGT etc) are bequeathed half-and-half to myself and my sister (who also lives abroad; I live in the UK).

The deposit box was opened almost 4 years ago. Does this mean there is tax to pay on the interest during that period and how do we go about paying it? Should I pay this here in the UK or to the Irish revenue?

The solicitor wants instructions to sell the shares. However as I had intended investing some of my portion of the legacy in the stock market to create a Trust fund for the great-grandchildren I am interested in maintaining my shares as they are.

Is this legal and what would the tax implications be?

P.S.

Perhaps I need to add that "the great-grandchildren" are my late mother's great-grandchildren and are Irish and resident in Ireland. There are three aged between 3 and 3 months with lots more in the pipeline.