Could be a fancy letter L -Little house
There maybe an entry in the BT's of the baptism that maybe clearer-These are held at the Borthwick institute at York University near York, North Yorkshire -They don't charge much for a copy on a known date
Possible
Silk Mill House,(Upperthong) Huddersfield Road, Holmfirth, HD9 4AW
Sillke
Its said Overthong was the old name for Holmfirth, Overthong is broadly (Rough area) the bottom of Thong lane from Netherthong where it meets Huddersfield road to Holmfirth centre at Cooper lane, basically lower east Upperthong to Netherthong and Thongsbridge being North of the river holme
Overthong is more known today as just Thong (The part of Holmfirth that in mostly in the Almondbury mother Parish)