My great grandfather Thaddeus (Timothy) Lavin (b1851) was from Danesfort/Killukin nr Carrick on Shannon. His father was a farmer, Edward and mother, Margaret Currigan/Cunningham. Edward's father was Thaddeus Lavin (b abt 1790) also from that area and Edward's mother, Margaret Cain/Keogh. Timothy settled in St Helens, Lancashire in the late 1870s or so. I understand that Timothy came to England with other family members of of his generation, but I have not heard of any Midlands connection - the family's knowledge is sketchy however. Lavin/Laven/Lavan is, I understand, a Connaught surname. It seems several Roscommon Lavins settled in Lancashire from the mid to late 1800s. Some are likely to be be related, but it is quite difficult to work out if relationships exist between the various Roscommon Lavins in Lancashire. Sorry I can't be of any further help.
CG nee Lavin born in St Helens early 50s