Hi Stephen
On the 1861 census there is the following family living in Bradford:
GOMERSALL, James Head age 45 Cordwainer born Woodhouse, Leeds.
Esther Wife age 43 born Birstal, Yorkshire
Matthew Son age 18 Coal Miner born Birstal
James Son age 16 Coal Miner, born Birstal
Samuel Son age 15 Coal Miner, born Birstal
Mary Daughter age 12 born Birstal
Henry Son age 8 born Drighlington, Yorks
Ann Daughter age 4 born Drighlington, Yorks
Tom Son age 2 born Drighlington, Yorks
The following on the 1891 census living in Yorkshire:
GOMERSALL, Matthew, Married age 48 a coal miner, born in Bristol
GOMERSALL, Emma Wife Married age 46 born in Davenport, Devonshire.
So it seems that your g.grandfather had quite a few brothers and sisters and that one of them was called Matthew and he married someone called Emma. This is presumably the couple who sent your grandfather a card, as they would be his uncle and aunt.
From the census it would seem that your g.grandfather was born around 1858/1859. There is a birth for a Malcolm William Gomersall in Barnsley in 1855 and a death for a Malcolm William Gomersall in Barnsley in 1884, who is presumably the Malcolm you mention.
Liz