I have a note/letter written to my grandfather Leslie Arthur Newton signed by someone with the surname Williams and underneather the signature it says Master, H.T. H,6

The letter has the number 2336040 written before Sgt and after my grandfathers name it says R.Sigs.

The letter says:
The above names soldier was detailed by the Officer Commanding Troops ton act as signallor on board my ship and i want to commond hom for the efficient way he carried out his duties - the proficiancy displayed during the voyage was of a very high standard."

It says at the bottom: "At sea 24th April 1945" so i guess this is when the letter was written.

I've tried to search the records for any information on my grandfathers service but have been unable to find anything.

Can you one help?