Three retailers boasted strong availability this week, but a short queue and friendly staff helped Sainsbury's in Alnwick scoop the top store award - fittingly on the very day it kicked off its 140th birthday celebrations.

Although staff were busy shelf-stacking, it did not stop them locating several items for our shopper, who described them as "very helpful and well trained". All 15 tills were open and the checkout assistant made polite conversation and handed our shopper a 140th anniversary bag for life.

Morrisons in Bredbury also had strong availability, helpful staff and a tidy store, but two tills were closed resulting in a longer queue.

Asda in Portsmouth, another store with good availability, was let down by a long queue and the aisles were somewhat congested because the store was so busy. The checkout assistant was chatty and offered to pack, however.

One out-of-stock item let down the otherwise impressive Waitrose in Cheltenham. Staff were busy shelf-stacking, but they left the trolleys at the end of the aisles so they did not get in our shopper's way. The checkout assistant was polite, although not as friendly as the staff around the store.

Availability disappointed at Tesco in Gateshead, with three out-of-stock items. Staff were busy shelf-stacking but escorted our shopper to several items and there were plenty of tills open.

Winner: Debra Thurley, store manager, Sainsbury's, Alnwick

How did the 140th anniversary celebrations go over the weekend? Really well. We had a huge cake to celebrate for our customers. Our customer service manager and a colleague who has been with Sainsbury's for 30 years cut it – and it was eaten within a few hours.

What are the advantages of being located in a tourist hotspot? Alnwick has a castle and gardens nearby and there are not many supermarkets in the area. Therefore summer holidays and half terms become particularly busy as many come here for a holiday and stay in self-catering accommodation. We usually see a big uplift in barbecue foods, summer toys and clothing during these periods. Morrisons is the only other supermarket in Alnwick and it is a similar size to ours. I think we are very competitive. Before our store opened last year, Morrisons had a large proportion of trade in the town. However, we have managed to take share from them and I think it is a lot more equal now.

Our shopper was impressed with her experience. How do you pull it off? It’s all about the combination of availability and service for the customer. My everyday management challenge is to make sure all the tasks on the shop floor get done, the shelves are kept full and the staff have smiles on their faces. I motivate them by listening, talking and understanding their needs at work.

Are you likely to expand your non-food offer? Non-food accounts for 5,000 sq ft of our 24,000 sq ft selling space and there is no room for any more. I would like to introduce an extended clothing range as well as a men’s range, though. I think an online service would work well too.

What’s selling particularly well at the moment? Our own-label ranges have been very successful. More and more shoppers are switching to our Basics range thanks to the Switch and Save and Feed Your Family for a Fiver campaigns. I think many have realised Basics products are really good quality and work well as ingredients. We have seen strong uplifts in our Basics meat, fresh and fish ranges. Our customers are also putting more Taste the Difference lines into their baskets as a treat.