Green’s Dictionary of Slang

fine, excellent, first-rate.

1841		W. Leman Rede Sixteen String Jack I iii: The dashy, splashy, leary little stringer, / Mounted his roan, and took the road— Phililoo!
1865		V.C. Giles Rags and Hope in Lasswell (1961) 256: Two splashing girls! Just as pretty as pinks and bully good Rebs.
1866		Letters by an Odd Boy 57: Six footmen (with calves), very splashy.
1902		H. Baumann Londinismen (2nd edn).
1905		‘Hugh McHugh’ You Can Search Me 53: Suppose a manager were to call in a rubberneck, hand him a tool box and send him to a newspaper office to look for a splashy production on a busy night.
1971		(con. 1930s) B. Short Black and White Baby 55: Another splashy social event was the annual minstrel show and ball given by one of my mother's clubs .
1999		Indep. on Sun. Culture 13 June 5: Every big splashy mainstream Hollywood film takes place in the future.
2005		A. Bennett Untold Stories (2006) 67: The aunties’ splashy behaviour [...] became a family joke.