Paint has bubbled a year later?

Paint usualy bubbles if the surface that you painted was freshly plastered and no sealer was applied to the plaster pva sealer or something similarshould be applied
.OR it could be dampness, damp under the paint surface turns to vapour streching the paint causing bubbles in the coating. CHECK FOR DAMP USING A DAMP METER OR LOOK FOR SIGNS OF MOULD IF SO DRY OUT WALL PAINT WITH A DAMP PROOFING LIQUID SEALER OR DAMP PROOF PAINT THEN EMULSION THIS SHOULD SOLVE YOUR PROBLEM.

ALEX FALKIRK.
September 2008