1200 Very Slight Coolant Leak.

You could try using Sugru for a temporary repair...
https://sugru.com
It fixed the Y shape hose issue for us...

 

Thanks for that Twins, hadn't heard of and now will try to keep on the bike. Along with zipties.

 

Just to add another coolant expansion tank failure to the list.

As others have previously mentioned, the source of the leak is from around the single fixing insert.

My bike is a low mileage 1200 DVT Multistrada (16 reg.)

Price of the new expansion tank was £51.42

Amongst other service work, the replacement was carried out by Desmo Shed in Barnet, North London who I can thoroughly recommend.