Receives usual care only.

Receives usual care plus Support 1 (MS Nurse Support) which includes one one-to-one, face-to-face session with an MS Nurse Specialist in a hospital setting (or via Skype). The session will include answering newly diagnosed patients' questions about MS, providing psychoeducation and teaching Acceptance and Commitment strategies (Hayes, Strosahl & Wilson, 1999), and referring to other services (based on needs). Participants will also be given a self-help workbook ('Better living with a diagnosis of MS: Patient Workbook') by the nurses. This session will take place within 2 weeks of diagnosis and last up to 90 minutes. It will be supplemented by phone calls (depending on participant needs). MS Nurses will receive training and on-going supervision from experienced clinical psychologists.

Receives usual care plus Support 2 (i.e. MS Nurse Support plus Peer Support). In addition to receiving the MS Nurse Support (i.e. Support 1, as described in Group 2), this group will also receive peer support which will be provided by Peer Support Workers who are patients/carers with lived experience and who are recruited and trained to deliver peer support under supervision from experienced clinical psychologists. It will be delivered one-to-one, face-to-face (in a community setting or via Skype, based on participants' preferences). Patients in this group will be triaged to a Peer Support Worker by the MS Nurse during the 2-week MS Nurse Support session. The sessions will be scheduled to a convenient time between weeks 2-6 after diagnosis and each session will last up to 60 minutes.

MS Nurse Support intervention is multi-faceted, involving various components (i.e. information provision and emotional support), and a range of strategies and techniques (e.g. psychoeducation, acceptance and commitment), delivered by MS Nurse Specialists, to provide standardised support and advice to patients at diagnosis, to establish and sustain coping strategies. MS Nurse Support intervention is person-centred and tailored to the needs and lifestyle of each participant.

[Note: As feasibility studies are used to estimate important parameters to inform the design of a full trial (NIHR, 2018), we outline the key outcomes related to feasibility. These are described below. Please see Outcome 1-15.]

Feasibility of trial procedures will be assessed through feedback interview (qualitative) data from participants and service providers (i.e., questions about the research process/procedures, and suggested changes to the study).

Assessed through feedback interview (qualitative) data from participants and service providers on the trial procedures.

Assessed through feedback interview (qualitative) data on randomisation protocol and willingness and acceptance of patients to be randomised.

Number of those eligible who expressed interest/discussed with researcher, number of consenting/randomised patients, reasons for non-participation, retention rates, feedback interview (qualitative) data.

Sample size calculated through effect sizes from ANOVAs, standard deviations and attrition rates.

Completion rates of outcome measures, number of missing online and postal data, estimates of time (minutes) taken to complete measures (from online/phone data or feedback interview data).

Perceived Stress Scale 4 (PSS4; Cohen, Kamarck, & Mersmelstein, 1983; Cohen & Williamson, 1988) to measure the level of perceived stress among people with MS by assessing their level of perceived uncontrollability and unpredictability on a 5 point scale (0=never, 1=almost never, 2=sometimes, 3=fairly often, 4=very often). The scores for each question are added (after reverse scoring two of the four questions) to give a total score ranging from 0 to 16, with higher scores indicating higher stress.