non EU spouse of a UK citizen

a maltese e-residence card is not a valid travel document  however accompanied with the passport can be used to show you have been living in an eu country and as long as your travelling with your eu spouse to the uk .. you will not need a visa.
it is worth noting that
"The UK does not accept Residence Cards issued by other states for entry into the UK"

if your visiting a non eu country then you will need the passport and any valid visa etc -

For transit to a non EU country I would not go via the UK. Try Frankfurt or some other Hub in the Schengen area.

Thanks, it's a bit of a minefield these days!

Thanks, ideally would transit via Frankfurt or Paris, but special low fare offer is via London.

If you are just transiting through the same airport, then this should not be an issue, as I just recently travelled to Malta via Heathrow from Singapore with my Filipina wife, without any problems (she didn't have a UK visa)

Check if you need a UK visa (gov.uk/check-uk-visa)

Also, these articles may be of interest to you:

Visa free travel for Residence Card holder Case refer to ECJ (immigrationboards.com/eea-route-applications/visa-free-travel-for-residence-card-holder-case-refer-to-ecj-t121226-80.html)

European court gives UK visa direction (bbc.com/news/uk-30528189)

Thanks, I'll check out this info, much appreciated. Does your wife have an EU common format residence permit or just a e-residence card?

She has neither

We applied for a Schengen visa, and then used that to enter Europe, then travel to Malta, where we have just applied for our e-residence cards (see other thread for full detatils)