there are a couple of nice little museums in cumbria that ive been to, theres the lakeland motor museum in haverthwaite on the road to barrow, its next door to the lakeside and haverthwaite steam railway so can be part of a good day out, the steam railway links onto the lake cruises on windermere, you can buy a ticket for the train and the boat, so if your other half doesnt want to look at old cars and motorbikes as well as toys, bicycles aircraft boats and caravans for a few hours, she or he could jump on the steam train and take a cruise on the lake with stop offs at windermere and ambleside.
alternatively, up in keswick, next door to the oft derided pencil museum, (yes, its a real place, based on the past mining of graphite in the area) there was once a james bond museum but i think its shut down now.