Plasterboard butts up against a ceiling beam and having siliconed the junction I now see it's pulled itself away from the wood. The wood was painted first and then silicone was applied. Not sure whether it was a high modulus one, probably just a general builder's silicone. As there's a slight movement here during warmer weather, it needs a flexible sealer. Any recommendations?

 

Plasterboard / painted wood junction:

 

 

https://www.toolstation.com/premium-building-silicone-310ml/p56400 - apparently sticks to wood (but probably not painted wood).

Why not just standard decorators chauk? It has flex to it, so will allow some movement.

You should wait 6 months after plastering and then use decorators caulk

Thanks. I've used caulk before but was never impressed with it as found it to crack after a while also and was not something I had considered using again. I'll give it a go and hopefully no issues with it this time.