Whatever it is, it's likely a family or provincial coat of arms and you may be able to track it down.
The four lions passant (one in each quarter of a shield) are sometimes used an indication of royal patronage, as on Cambridge University's coat of arms. They also have long-standing use as the badge of Wales (and the Prince of Wales), although not with a cross separating the quarters.
You'll need to research specific combinations of heraldic devices and colours though rather than just look for 'similarities'. Cambridge University's coat of arms for example has the lions on a red field, the cross is 'ermined' (has small representations of the stoat's tail dotted across it) and has a bible at the centre.
Yours has something dotted across the lateral arms of the cross, but it's not ermined (those are 'lozenges' perhaps, but aren't very clear from the picture) and something at the centre which may be a saltire (an 'X' shaped cross) with something at its centre. These shields were often enamelled, so have a really good look with a loupe for even the tiniest traces of colouration remaining from enamelling that has since corroded away.
In the absence of any colour indications, you can probably assume that the lions were gold/yellow ('or') or, less likely, silver ('argent'). Heraldic convention is also that red ('gules') is represented by parallel vertical lines, so the field that they're on is/was probably that colour. A plain surface (apart from patterning with ermine spots and such) is the usual convention for silver/white, so the cross may have been that colour.
Good luck.
