Often when a horse has not run much or at all on the current ground conditions at the track where he's racing next, he will have run on the next drier and/or the next wetter ones. For instance if he's never run on GS but has several races on G and S, I take his combined performance on the both of the latter ground conditions as a good proxy for how he should do on GS. I wrote a spreadsheet macro that combines the two.
But Irish racing has finer grades with different abbreviations and I'm not sure which Irish track condition corresponds to which British one. Does anyone know, which Irish denotations correspond to GF, G, GS, S, and HY? They seem to have finer grades so that complicates a little.