Thank you both, clearly there are avenues to follow. Will certainly search out the books and newspaper reports mentioned, as well as contacting the RNLI at Holyhead.
Tall All and I are distant cousins who found each other via family tree searches - thanks for your pointers - hope to meet up soon
To Seaweed, thank you in particular for pointing out that Edward Hughes (father of the drowned brothers was also on board that day) - I was not aware of this, but helps to confirm my suspicion that the Hughes family from Cymyran were indeed quite heavily involved with Rhoscolyn Lifeboat.
Found a good photo of the Lifeboat crew on the Internet, including two with the Hughes surname, but since there is no date for the photo - unable to possibly put faces to names.
Am looking forward to learning more, thanks again