Indeed. The alternator diode pack died and was overcharging the battery. This caused the battery to get hot and expand, check the boot to see if this is the case but exercise extreme caution and cover your eyes.
If the diode pack is ok and the alternator is dying, the battery light will be on as sufficient charge (14v) will not be reaching the battery.
To confirm this, with the engine running put a multimeter across the battery terminals (don't rely on the gauge) and it should read over 14v, should be 14.5v ideally.
If all this seems fine, then check the terminals. I have seen them crack, can be remidied with a jubilee clip and also check the condition of the cables to the battery and the earth where it attaches to the body. For this, you will need to remove the right hand carpet trim round the battery.
And finally, just to rule it out, disconnect the battery for half an hour, then reconnect, remembering not to shut the boot and to drop the drivers window a little first.
Might as well shove this in as well, whilst I am at it:
Main fuse panel, under passenger footwell mat...
F5-30A-Headlight washer timer
F44-30A-+30 Driver's seat
F45-30A-+30 Passenger's seat
F46-7,5A-Passenger's seat heating
F47-7,5A-Driver's seat heating
F50-7,5A-Air conditioning and ventilation unit
R8-30A-Connected devices cut out during ignition
R9-30A-Connected devices not cut out during ignition
R17-20A-Passenger's seat heating
R18-20A-Driver's seat heating
F9-10A-+87 main relay
F10-15A-+87 Lambda sensor main relay , air flow meter
F11-15A-+87 main relay for injectors, coils
R10-20A-A.C. Compressor, horns
F32-10A-RH High beam light
F33-10A-LH High beam light, warning light
F35-15A-Left-hand low beam
F36-15A-Right-hand low beam, headlight washers inhibitor switch, manual headlight angle adjuster
R12-20A-High beam lights
R13-20A-Low beam lights
F6-10A-Headlight washer timer
F12-15A-+30 ignition switch
F14-5A-Air conditioning and ventilation system, navigator cable bundle, (+15 connected devices cut out during ignition)
F15-15A-Cigarette lighter, radio, engine indic., rear view mirrors, ceiling light, glove compartment lamp (+15 cut out during ignition)
F17-25A-Windshield wiper, windshield wiper washing pumps, wiper(+15 cut out during ignition)
F18-10A-Airbag (+15 connected devices not cut out during ignition)
F19-5A-+15 NCS (+15 connected devices not cut out during ignition)
F20-7,5A-Immobilizer, CAN line interface, navigator cable bundle instrument(+15 not cut out during ignition)
F21-5A-Alarm system, preset for satellite alarm
F22-10A-Ceiling lights, ceiling light timer, (electronic) seats , luggage compartment and fuel flap opening controls
F23-7,5A-ECU for CAN line interface, OBD, Maserati CODE system, multifuncion display
F24-20A-Door locking system
F26-30A-Driver side power windows
F27-30A-Passenger side power window
F30-10A-+15 light switch, Cruise Control, headlight aiming ECU (+15 cut out during ignition)
F31-15A-Turn signal light blinking
F37-15A-+30 IGE ECU
F38-15A-+30 IGE ECU
F39-5A-IGE ECU, ceiling light timer, light switch (+15 connected devices not cut out during ignition)
F53-10A-Navigator, clock, tunnel display
F70-15A-Exhaust bypass solenoid valve
Well I got the alternator going by waggling the alternator connector -but there was never a charging light warning. The dipped headlights are not working now but the beep beep has stopped and the tail lights are off. At this point the local euro car rescue has carried us to a hotel and euro assist are supposed to be getting us a hire car at 9 am. Trouble is we cant take a hire car home so will have to fly back at our expense and get the car shipped home... ALL Maserati dealerships are apparently closed until September because of holidays so we can't get the car fixed in Italy! The annoying thing is that we could have got to a Maserati dealer in Ancona before they closed but they never answered the phone and the rescue truck would not take us there if they were closed...
Finally to add to the pain the rescue truck ramp was too steep and the car grounded at the rear.