DR J WATT, of Dartmouth, writes:

The superyacht Vanish is a fine sight moored in the middle of the river. What a pity her arrival was spoilt by an ­incorrect courtesy flag, which should have been our maritime flag, the red ensign.

However, she wore the Union flag, but unfortunately it was upside down.

Did the harbour staff not notice this and advise her accordingly? Perhaps they should carry a spare red ensign in the pilot cutter to save

any further embarrassment to ­visiting superyachts.

Only British warships are permitted to use the Union flag when at anchor or alongside, when it is known as the Union Jack.