Under Tools/Add-ons/Dictionaries, is the British dictionary installed and enabled?

Yes, I have checked. It is installed and enabled. The path is actually Tools => Add-ons => Languages, but I am only offered 'Disable ' and 'Remove'. The 'spell check' box that opens on 'Send' still has the language field greyed out.

'Languages' and 'Dictionaries' are distinct: the former applies to the menus and dialogues, while the latter is for spell-checking. To install the dictionary cited in my first reply, drag the green 'Download Now' button and drop it onto the Tools/Add-ons window in TB. Once installed, you should see the option in the Language drop-down under Tools/Options/Composition/Spelling.

Thanks. Your advice was a little terse for a beginner in TBird, but I managed to interpret it.

UPDATE: T-Bird has changed a lot in locations since this was published.

In T-Bird click the 3 stripes hamburger icon at the TOP RIGHT of the program, near the search bar field.

No need to go into TOOLS anymore, there is a dedicated menu for ADD-ONS . It has a jigsaw piece icon next to it.

Okay - download the Brit Dictionary (not language) in your browser, don't open it if you have Chrome or Pale Moon installed as it will try to install it there instead. Download it here: [https://addons.mozilla.org/en-us/thun.../?src=cb-dl-mostpopular]

Save the file instead into your download folder.

Press Win+ E to open File manager and find the Brit dictionary

Meanwhile in T-Bird have the ADD-ONS tab open on DICTIONARIES.

Drag the Brit Dictionary from your down load folder to the T-Bird Dictionary tab and it installs immediately.

Yes, I agree it is entirely unnecessary faff and defies the concept of an easy to configure e-mail program, but it works.

Case closed (a long time ago in fact)

But the instructions are WRONG

I have just tried to follow them, so this helping other people who do not enjoy a terse, hard to follow reply.

PC Tutor (Senior)