thanks valmai3, - your 2018 mail and this week's were already a good help.
Piecing it together, I get the following:
Movements of the 58th Regiment of Foot (Rutlandshire) -1828-1859
In Ceylon, India from 1828 to 1839 (after taking part in Peninsular War)
To England (Portsmouth/Gosport) June 1839
To Glasgow from Gosport in July 1840 -so a year in Gosport, but where? (And in February 8 1840 Naval and Military Gazette the 58th were rumoured to go off to Cork on “The Jupiter”, i.e. Fermoy Barracks, where some soldiers of the regiment were in 1834, while the rest were in Ceylon. The Jupiter was much delayed returning with the 61st from Ceylon, and in March had to go into Cork b/c strong east wind in Channel. Then refit. -they did not go to Cork)
Still in Scotland 1841 (Glasgow and Edinburgh), but also in Richmond Barracks, Dublin. (Recruiting in Scotland or pre-1845 stirrings? )
Still in Dublin July 1842 (cf birth in officer’s family)
To New South Wales, Australia, in July 1843 (gradually, some soldiers as guards on 19 convict ships 1843-45)
On to New Zealand from Sydney in March-April 1845, (ships North Star, Slains Castle) Bay of Islands, North Island, Auckland. Flagstaff Wars. (some back and forth Sydney-NZ)
Back from New Zealand in March 1859 (started out in November 1858), many, over 300 men, discharged in NZ.
The 58th today is the 3rd battaillon 'Steelbacks' of the Royal Anglian Regiment with HQ in Bury St. Edmonds - so I might ask if the museum there has further details :-)
How usual was it for a regiment to be split up for several years?. Its major-general Grant actually died in 1841 en route from Glasgow to Dublin, at Tontine Inn