I have gone ahead and cleared the area and the perimeter and raked it all out. Taken most of the day. The mice are running now.
Incidentally, my cat would have had one but she leapt into the chicken wire fence and rebounded quite sheepishly. Dont think she knew it was there, she is only just going out and about here since the move. Stupid cat! But good going for a twelve year old townie cat with more fur than meat on her (she's tiny and very fluffy, another rescue job I lumbered myself with yrs ago).