2.
I have assumed, from the Trinity College data, that Robert's father was William Halpin and a soldier. There are only two Halpins in the Army Lists in 1831 to about 1860 (other than surgeon Oliver), both called William, one of which was in the Indian Army (EIC) [of whom more later]. The other William Halpin was a Paymaster in the 1st Light Dragoons, King's German Legion: he was commissioned as Paymaster on 6th January 1807 in Ireland [The King's German Legion was formed in 1803, HQ in Bexhill on Sea and Weymouth but almost all quartered in Ireland from about 1806 - several thousand men, in infantry and cavalry regiments - of which there is an interesting history, too much to go into here] - although most officers were German, most of the paymasters of the different regiments appear to have been British. Paymasters were staff officers and wore distinctive uniforms, although only ranking as captains. William Halpin served with the 1st Light Dragoons in the Peninsular War and received the War Medal with clasps for Salamanca, Vittoria, Orthes and Toulouse; on Challis's Peninsular Roll he is listed as Wilhelm Halpin but in the History of the King's German Legion (by Beamish from Cork, where the German Legion troops all landed) published in 1832 and 1837, he is listed as Paymaster William Halpin 1st Dragoons, with service in the Peninsular 1812-1813, South of France 1813-1814, the Netherlands 1814 and on the 1815 Campaign (although not on the Waterloo roll). So it may well be possible that Robert Crawford Halpin was born in France or Belgium. [While doing this I also came across a James Halpin born in Cambrai, France, in 1816]. The KGL, which had notable service, both in the Peninsular (1st Dragoons battle honour, Garcia Hernandez) and at Waterloo (La Haye Sainte farmhouse), was disbanded in 1816, the Light Dragoons (which were part of the KGL attached to the Anglo-Belgian Army) at Celle in Germany (Hanover) on 24 February 1816; all officers not going into the re-constituted Hanoverian Army were placed on half pay. The Colonel in Chief of the KGL interestingly was Field Marshall Adolphus Duke of Cambridge, father of the George above. From the Army lists from 1831 to 1864, Paymaster William Halpin in consistently listed as on half pay, finally listed as died in 1864. The 1861 census for England has a William Halpin, widower, Captain h.p. 1st Light Dragoons living at 39 Leinster Square, Bayswater, London; he is recorded as being 84 years old, i.e. born about 1777, born in Wicklow, Ireland (Connection to your Halpins at last!!) with two unmarried daughters Anna (b 1808, Wicklow) and Sophia (b 1811, Wicklow) and a son William (unmarried, b 1801, Limerick). William Halpin "junior" is described as a Colonel Madras Army (thus must be the other William Halpin in the Army Lists - see above). Captain William Halpin died in December 1862 and was buried in All Souls Cemetery, Kensal Green, London on 31st December 1862. There is no trace of the family in the 1851 census, so my guess is that they were in Ireland before about 1860. Interestingly 'Major General' William Halpin died "aged 60" in April 1865 and was buried in All Souls Cemetery on 28 April 1865; his address was given as 54, Belsize Road, Hampstead (see Robert above). The two daughters / sisters do not appear in the 1871 census so I guess they may have returned to Ireland. If William was born in 1777 he was about 29 when he was commissioned - it would be interesting to know what he was doing before that.
Thus "my" Halpins do come from Wicklow and are almost certainly related to your own families - I will be interested to see if William fits in with your data - any ideas who his wife may have been? Unfortunately though, none of this gets me any nearer my George Halpin and his wife Kate Wemyss or where they went after 1881 in Scotland or how Goerge got to Buenos Aires!
Thanks for your help and for introducing an interesting area for research. I will follow further postings with interest.
Ronald