We are suddenly having to scramble for a possible UK visit over Xmas with a newborn baby, leaving a host of questions (mainly, is it even possible):

Does a first-time passport application still go though the DHL and Hong Kong channel or does it require a visit to the embassy in Bangkok?

From experience, how long does the above process take place?

Is there an express option?

Are embassies likely to remain open during current flood situation?

If a visit to the embassy is required, does only the applicant (the baby) and the UK citizen parent need to attend (as opposed to the whole family)?

Finally, 5-year-old daughter's passport also needs renewal, if baby's passport can be applied for by post can we lump both applications in the same envolope and save some money?

Thanks in advance for any advice or personal experiences given

No recent experience, but see:-

How to apply from Thailand (First time applications)

How to apply from Thailand (Renewals)

The Bangkok embassy home page says

The British Embassy is open, but due to the current flood crisis in Bangkok we are able to offer only a limited service. If you wish to visit the Embassy please call us before visiting on + 66 (0) 2 305 8333.

This information may be almost 1 year old now..

When I got my son's birth certificate in BKK, I was asked whether I want to do his Passport Application at the same time (at the embassy).

I would have to apply to Hong Kong for mine, but it seems that a first application could still be done at the embassy.