Hmm, that's a tricky one. Quite a few pressed glass makers did something like this, most commonly around 1855 to 1860. Yours is a close match in parts to an Edward Moore version, but not the same. The style of creamer is one I would heavily associate with the northeast. I can't see this in the 1874 Sowerby catalogue (though it could have been a discontinued design). Therefore I would put Henry Greener in pole position (or rather, Angus & Greener at that date), with discontinued Sowerby design in second place. Could be wrong though.